Zoom lens system

ABSTRACT

A zoom lens system for forming an image of an object on a solid state imaging device includes a first lens unit having a positive optical power and being movable in a zooming operation; a second lens unit having a negative optical power; and a third lens unit having a positive optical power. The system satisfies at least one the following conditions: 0.8&lt;M 1 WM/M 1 MT&lt;2.5; 0.2&lt;Δβ 3/Δβ2 &lt;1.0; 0.7&lt;m 1 /Z&lt;3.0; 1.0&lt;img*R&lt;15.0; 1.0&lt;max(T 1,  T 2,  T 3 )&lt;4; and 4.5&lt;fT/|f 12 W|&lt;15, where M 1 WM represents movement amount of first lens unit from shortest focal length condition to middle focal length condition; M 1 MT represents movement amount of first lens unit from middle focal length condition to longest focal length condition; Δβ 2  represents lateral magnification ratio of second lens unit; Δβ 3  represents lateral magnification ratio of third lens unit; m 1  represents movement amount of first lens unit in zooming operation; Z represents zoom ratio fT/fW; fW is system focal length at shortest focal length condition; fT represents system focal length at longest focal length condition; img represents maximum image height; R represents effective diameter of lens surface which is closest to image side among lens surfaces constituting zoom lens system; Ti is axial thickness of an i-th unit; max(T 1,  T 2,  T 3 ) is maximum thickness; and f 12 W represents a composite focal length of first and second lens units at shortest focal length condition.

[0001] This application is based on Japanese patent application Nos.9-265394, 9-265395, 9-265396, 9-265397, and 9-265398 filed on Sep. 30,1997, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a zoom lens system which is usedin a small-sized imaging optical system, and more particularly to acompact zoom lens system of a high variable magnification which is usedin an imaging optical system of a digital input/output apparatus, e.g.,a digital still camera or a digital video camera.

DESCRIPTION OF THE RELATED ART

[0003] Recently, with the increased use of personal computers, digitalcameras (e.g., digital still cameras, digital video cameras, and thelike; hereinafter, such a camera is referred to simply as a digitalcamera), which can easily transfer video information to a digitalapparatus, are becoming popular at the private user level. It isexpected that in the future such a digital camera is further widespreadwill be widely employed as an input apparatus for video information.

[0004] Usually, the image quality of a digital camera depends on thenumber of pixels of a solid state imaging device, e.g., a CCD (chargecoupled device). At present, most digital cameras for general consumeruse employ a solid state imaging device of the so-called VGA classhaving about 330,000 pixel resolution. However, it is not deniable thatthe image quality of a camera of the VGA class is largely inferior tothat of a conventional camera using a silver halide film. Thus, in thefield of digital cameras for general consumer use, a camera of a highimage quality and having a pixel resolution of 1,000,000 or higher isdesired. Consequently, it is also desirable that the imaging opticalsystem of such a digital camera satisfy a requirement of a high imagequality.

[0005] Furthermore, it is desirable that these digital cameras forgeneral consumer use perform magnification of an image, particularlyoptical magnification in which image deterioration is low in magnitude.Therefore, a zoom lens system for a digital camera should satisfy therequirements of a high variable magnification and a high image quality.

[0006] However, among zoom lens systems for digital cameras which havebeen proposed, most of the systems having a pixel resolution of1,000,000 or higher are those in which an interchangeable lens for asingle-lens reflex camera is used as it is or those for a large-sizeddigital camera for business. Therefore, such zoom lens systems are verylarge in size and high in production cost, and are not suitable for adigital camera for general consumer use.

[0007] By contrast, it may be contemplated that an imaging opticalsystem of a lens shutter camera, which uses a silver halide film and inwhich compactness and variable magnification have recently noticeablyadvanced, is used as the imaging optical system of such a digitalcamera.

[0008] However, when an imaging optical system of a lens shutter camerais used as it is in a digital camera, the focal performance of amicro-lens disposed in front of the solid state imaging device of thedigital camera cannot be sufficiently satisfied, thereby producing aproblem in that the brightness in the center area of an image is largelydifferent from that in the peripheral area of the image. Specifically,this problem is caused by the phenomenon that the exit pupil of animaging optical system of a lens shutter camera is located in thevicinity of the image plane and hence the off-axis beams emitted fromthe imaging optical system are obliquely incident on the image plane.When the position of the exit pupil of an imaging optical system of alens shutter camera of the prior art is separated from the image planein order to solve the problem, the size of the whole imaging opticalsystem is inevitably increased.

SUMMARY OF THE INVENTION

[0009] It is an object of the invention to solve the above-discussedproblem.

[0010] It is another object of the invention to provide a zoom lenssystem which can satisfy the requirements of a high variablemagnification and a high image quality.

[0011] In order to attain the objects, the zoom lens system comprises,from the object side, a first lens unit having a positive optical power,a second lens unit having negative refractive power, and a third lensunit having a positive refractive power, wherein the zoom lens systemfulfills the predetermined conditions.

[0012] In the invention, a zoom lens system comprises, from the objectside of the zoom lens system to the image side of the zoom lens:

[0013] a first lens unit having a positive optical power, the first lensunit being movable in a zooming operation;

[0014] a second lens unit having a negative optical power; and

[0015] a third lens unit having a positive optical power,

[0016] wherein the zooming operation can be performed by varying thedistances between adjacent ones of the first, second, and third lensunits.

[0017] In a first embodiment of the invention, the zoom lens systemsatisfies at least the following condition:

0.8<M 1 WM/M 1 MT<2.5

[0018] where

[0019] M1WM represents a movement amount of the first lens unit from theshortest focal length condition to a middle focal length condition; and

[0020] M1MT represents a movement amount of the first lens unit from themiddle focal length condition to the longest focal length condition, themiddle focal length being a focal length which is (fW/fT)^(1/2) where fWis a focal length of the entire zoom lens system at the shortest focallength condition and fT is a focal length of the entire zoom lens systemat the longest focal length condition.

[0021] In another embodiment of the invention, the zoom lens systemsatisfies at least the following condition:

0.2<Δβ3/Δβ2<1.0

[0022] where

[0023] Δβ2 represents a ratio of the lateral magnification of the secondlens unit at the longest focal length condition to the lateralmagnification of the second lens unit at the shortest focal lengthcondition; and

[0024] Δβ3 represents a ratio of the lateral magnification of the thirdlens unit at the longest focal length condition to the lateralmagnification of the third lens unit at the shortest focal lengthcondition.

[0025] In another embodiment of the invention, the zoom lens systemsatisfies at least the following condition:

0.7<m 1/Z<3.0

[0026] where

[0027] m1 represents a movement amount of the first lens unit in thezooming operation from the shortest focal length condition to thelongest focal length condition; and

[0028] Z represents a zoom ratio (Z=fT/fW: where fW is a focal length ofthe entire zoom lens system at the shortest focal length condition andfT is a focal length of the entire zoom lens unit at the longest focallength condition).

[0029] In a further embodiment of the invention, the zoom lens systemsatisfies at least the following condition:

1.0<img*R<15.0

[0030] where

[0031] img represents a maximum image height; and

[0032] R represents an effective diameter of a lens surface which isclosest to the image side among the lens surfaces constituting the zoomlens system. Preferably, the third lens unit can comprise, from theobject side to the image side, a positive lens element convex to theobject side and a negative lens element.

[0033] In another embodiment of the invention, the zoom lens systemsatisfies at least the following conditions:

1.0<max(T 1, T 2, T 3)<4

4.5<fT/|f 12 W|<15

[0034] where

[0035] Ti is the axial thickness of an i-th unit;

[0036] max(T1, T2, T3) is the maximum value of the thickness;

[0037] fT represents a focal length at the longest focal lengthcondition; and

[0038] f12W represents a composite focal length of the first and secondlens units at the shortest focal length condition.

[0039] In each embodiment, the first and third lens units or all threeof the lens units can be movable in the zooming operation so that afirst distance between the first and second lens units increases and asecond distance between the second and third lens units decreases.

[0040] A zoom lens system in accordance with the invention can beemployed for forming an image of an object on a solid state imagingdevice. Filters, including an optical low-pass filter and an infraredblocking filter, can be provided between the lens units and the solidstate imaging device.

[0041] The invention itself, together with further objects and attendantadvantages, will be understood by reference to the following detaileddescription taken in conjunction with the accompanies drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 1 at the shortest focal length condition;

[0043]FIG. 2 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 2 at the shortest focal length condition;

[0044]FIG. 3 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 3 at the shortest focal length condition;

[0045]FIG. 4 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 4 at the shortest focal length condition;

[0046]FIG. 5 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 5 at the shortest focal length condition;

[0047]FIG. 6 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 6 at the shortest focal length condition;

[0048]FIG. 7 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 7 at the shortest focal length condition;

[0049]FIG. 8 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 8 at the shortest focal length condition;

[0050]FIG. 9 is a cross sectional view of the lens arrangement of a zoomlens system of Embodiment 9 at the shortest focal length condition;

[0051] FIGS. 10(a) to 10(i) are aberration diagrams of numericalEmbodiment 1;

[0052] FIGS. 11(a) to 11(i) are aberration diagrams of numericalEmbodiment 2;

[0053] FIGS. 12(a) to 12(i) are aberration diagrams of numericalEmbodiment 3;

[0054] FIGS. 13(a) to 13(i) are aberration diagrams of numericalEmbodiment 4;

[0055] FIGS. 14(a) to 14(i) are aberration diagrams of numericalEmbodiment 5;

[0056] FIGS. 15(a) to 15(i) are aberration diagrams of numericalEmbodiment 6;

[0057] FIGS. 16(a) to 16(i) are aberration diagrams of numericalEmbodiment 7;

[0058] FIGS. 17(a) to 17(i) are aberration diagrams of numericalEmbodiment 8; and

[0059] FIGS. 18(a) to 18(i) are aberration diagrams of numericalEmbodiment 9.

[0060] In the following description, like parts are designed by likereference numbers throughout the several drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Hereinafter, preferred embodiments of the invention will bedescribed with reference to the accompanying drawings.

[0062] In the specification, the term “power” means a quantity which isdefined by the reciprocal of a focal length, and includes not only thedeflection in the faces of media having refractive indices of differentdeflection functions, but also the deflection due to diffraction, thedeflection due to the distribution of refractive index in a medium, andthe like. Furthermore, the term “refractive power” means a quantitywhich belongs to the above-mentioned “power”, and which is particularlydue to a deflection function generated in an interface between mediahaving different refractive indices.

[0063] The zoom lens system of Embodiment 1 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a doublet lens element DL1 composed of a negativemeniscus lens element L1 having a convex surface on its object side anda bi-convex positive lens L2, and a positive meniscus lens element L3having a convex surface on its object side; a second lens unit Gr2comprising a negative meniscus lens element L4 (both faces of which areaspherical surfaces) having a convex surface on its object side, and adoublet lens element DL2 composed of a biconcave negative lens elementL5 and a bi-convex positive lens L6; a diaphragm S; a third lens unitGr3 comprising a positive meniscus lens element L7 having a convexsurface on its object side, a negative meniscus lens element L8 (bothfaces of which are aspherical surfaces) having a convex surface on itsobject side, a bi-convex positive lens L9, and a bi-convex positive lenselement L10 (both faces of which are aspherical surfaces); and alow-pass filter F. In a zooming operation from the shortest focal lengthcondition to the longest focal length condition, the first and thirdlens units Gr1 and Gr3 are moved toward the object side, the second lensunit Gr2 is moved toward the image side, and the diaphragm S and thelow-pass filter F are kept stationary.

[0064] The zoom lens system of Embodiment 2 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a negative meniscus lens element Li having a convexsurface on its object side, a positive meniscus lens element L2 having aconvex surface on its object side, and a positive meniscus lens elementL3 having a convex surface on its object side; a second lens unit Gr2comprising a negative meniscus lens element L4 having a convex surfaceon its object side, a bi-convex positive lens element L5, and a doubletlens element DL1 composed of a positive meniscus lens element L6 (thefront face of which is an aspherical surface) having a convex surface onits image side, and a bi-concave negative lens element L7 (the rear faceof which is an aspherical surface); a diaphragm S; a third lens unit Gr3comprising a bi-convex positive lens element L8 (the front face of whichis an aspherical surface), a bi-convex positive lens element L9, anegative meniscus lens element L10 having a convex surface on its objectside, a negative meniscus lens element L11 having a convex surface onits image side, and a bi-concave negative lens element L12 (both facesof which are aspherical surfaces); and a low-pass filter F. In a zoomingoperation from the shortest focal length condition to the longest focallength condition, the first and third lens units Gr1 and Gr3 are movedtoward the object side, the second lens unit Gr2 is moved toward theimage side, and the diaphragm S and the low-pass filter F are keptstationary.

[0065] The zoom lens system of Embodiment 3 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising of a negative meniscus lens element L1 having a convexsurface on its object side, a positive meniscus lens element L2 having aconvex surface on its object side, and a positive meniscus lens elementL3 having a convex surface on its object side; a second lens unit Gr2comprising a negative meniscus lens element L4 having a convex surfaceon its object side, a bi-convex positive lens element L5, and a doubletlens element DL1 composed of a positive meniscus lens element L6 (thefront face of which is an aspherical surface) having a convex surface onits image side and a bi-concave negative lens element L7 (the rear faceof which is an aspherical surface); a diaphragm S; a third lens unit Gr3comprising a bi-convex positive lens element L8 (the front face of whichis an aspherical surface), a bi-convex positive lens element L9, anegative meniscus lens element L10 having a convex surface on its objectside, and a bi-concave negative lens element L11 (both faces of whichare aspherical surfaces); and a low-pass filter F. In a zoomingoperation from the shortest focal length condition to the longest focallength condition, the first and third lens units Gr1 and Gr3 are movedtoward the object side, the second lens unit Gr2 is moved toward theimage side, and the diaphragm S and the low-pass filter F are keptstationary.

[0066] The zoom lens system of Embodiment 4 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a doublet lens element DL1 composed of a negativemeniscus lens element L1 having a convex surface on its object side anda bi-convex positive lens L2, and a positive meniscus lens element L3having a convex surface on its object side; a second lens unit Gr2comprising a negative meniscus lens element L4 (both faces of which areaspherical surfaces) having a convex surface on its object side, and adoublet lens element DL2 composed of a bi-concave negative lens elementL5 and a bi-convex positive lens L6; a diaphragm S; a third lens unitGr3 comprising a positive meniscus lens element L7 having a convexsurface on its object side, a negative meniscus lens element L8 (bothfaces of which are aspherical surfaces) having a convex surface on itsobject side, a bi-convex positive lens L9, and a bi-concave negativelens element L10 (both faces of which are aspherical surfaces); and alow-pass filter F. In a zooming operation from the shortest focal lengthcondition to the longest focal length condition, the first and thirdlens units Gr1 and Gr3 are moved toward the object side, the second lensunit Gr2 is moved toward the image side, and the diaphragm S and thelow-pass filter F are kept stationary.

[0067] The zoom lens system of Embodiment 5 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a negative meniscus lens element L1 having a convexsurface on its object side, a bi-convex positive lens element L2, and apositive meniscus lens element L3 having a convex surface on its objectside; a second lens unit Gr2 comprising a negative meniscus lens elementL4 having a convex surface on its object side, a bi-convex positive lenselement L5, and a doublet lens element DL1 composed of a positivemeniscus lens element L6 (the front face of which is an asphericalsurface) having a convex surface on its image side and a bi-concavenegative lens element L7 (the rear face of which is an asphericalsurface); a diaphragm S; a third lens unit Gr3 comprising a positivemeniscus lens element L8 having a convex surface on its object side, abi-convex positive lens element L9, a bi-concave negative lens elementL10, and a positive meniscus lens element L11 (the rear face of which isan aspherical surface) having a convex surface on its object side; and alow-pass filter F. In a zooming operation from the shortest focal lengthcondition to the longest focal length condition, the first and thirdlens units Gr1 and Gr3 and the diaphragm S are moved toward the objectside, the second lens unit Gr2 makes a U-turn in which the lens unit Gr2is first moved toward the object side and then is moved toward the imageside, and the low-pass filter F is kept stationary.

[0068] The zoom lens system of Embodiment 6 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a doublet lens element DL1 composed of a negativemeniscus lens element L1 having a convex surface on its object side anda bi-convex positive lens element L2, and a positive meniscus lenselement L3 having a convex surface on its object side; a second lensunit Gr2 comprising a negative meniscus lens element L4 (the front faceof which is an aspherical surface) having a convex surface on its objectside, a bi-concave negative lens element L5, a bi-convex positive lenselement L6, and a negative meniscus lens element L7 (the rear face ofwhich is an aspherical surface) having a convex surface on its imageside; a diaphragm S; a third lens unit Gr3 comprising a bi-convexpositive lens element L8 (the front face of which is an asphericalsurface), a negative meniscus lens element L9 having a convex surface onits object side, and a positive meniscus lens element L10 (the rear faceof which is an aspherical surface) having a convex surface on its objectside; and a low-pass filter F. In a zooming operation from the shortestfocal length condition to the longest focal length condition, the firstand third lens units Gr1 and Gr3 and the diaphragm S are moved towardthe object side, the second lens unit Gr2 makes a U-turn in which thelens unit is first moved toward the object side and then is moved towardthe image side, and the low-pass filter F is kept stationary.

[0069] The zoom lens system of Embodiment 7 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising of a doublet lens element DL1 composed of a negativemeniscus lens element L1 having a convex surface on its object side anda bi-convex positive lens element L2, and a positive meniscus lenselement L3 having a convex surface on its object side; a second lensunit Gr2 comprising a negative meniscus lens element L4 (the front faceof which is an aspherical surface) having a convex surface on its objectside, and a doublet lens element DL2 composed of a bi-concave negativelens element L5 and a bi-convex positive lens element L6; a diaphragm S;a third lens unit Gr3 comprising a bi-convex positive lens element L7(the front side of which is an aspherical surface), a negative meniscuslens element L8 having a convex surface on its object side, a doubletlens element DL3 composed of a negative meniscus lens element L9 havinga convex surface on its object side and a positive meniscus lens elementL10 having a convex surface on its object side, and a positive meniscuslens element L11 (the front side of which is an aspherical surface)having a convex surface on its object side; and a low-pass filter F. Ina zooming operation from the shortest focal length condition to thelongest focal length condition, the first and third lens units Gr1 andGr3 and the diaphragm S which is integrated with the third lens unit Gr3are moved toward the object side, the second lens unit Gr2 is movedtoward the image side, and the low-pass filter F is kept stationary.

[0070] The zoom lens system of Embodiment 8 is configured along theoptical axis in the sequence from the object side by: a first lens unitGr1 comprising a negative meniscus lens element L1 having a convexsurface on its object side, a bi-convex positive lens element L2, and apositive meniscus lens element L3 having a convex surface on its objectside; a second lens unit Gr2 comprising a negative meniscus lens elementL4 having a convex surface on its object side, a bi-concave negativelens element L5, and a positive meniscus lens element L6 (both faces ofwhich are aspherical surfaces) having a convex surface on its objectside; a diaphragm S; a third lens unit Gr3 comprising a positivemeniscus lens element L7 having a convex surface on its object side, abi-convex positive lens element L8, and a negative meniscus lens elementL9 (both faces of which are aspherical surfaces) having a convex surfaceon its object side; and a low-pass filter F. In a zooming operation fromthe shortest focal length condition to the longest focal lengthcondition, the first and third lens units Gr1 and Gr3 are moved towardthe object side, the second lens unit Gr2 is moved toward the imageside, the diaphragm S makes a U-turn in which the diaphragm is firstmoved toward the object side and then is moved toward the image side,and the low-pass filter F is kept stationary.

[0071] The zoom lens system of Embodiment 9 is configured in thesequence from the object side by: a first lens unit Gr1 comprising adoublet lens element DL1 composed of a negative meniscus lens element L1having a convex surface on its object side and a bi-convex positive lenselement L2, and a positive meniscus lens element L3 having a convexsurface on its object side; a second lens unit Gr2 comprising a negativemeniscus lens element L4 (the rear face of which is an asphericalsurface) having a convex surface on its object side, a bi-concavenegative lens element L5, and a bi-convex positive lens element L6; adiaphragm S; a third lens unit Gr3 comprising a bi-convex positive lenselement L7 (the front side of which is an aspherical surface), anegative meniscus lens element L8 having a convex surface on its objectside, and a bi-convex positive lens element L9 (the rear side of whichis an aspherical surface); and a low-pass filter F. In a zoomingoperation from the shortest focal length condition to the longest focallength condition, all the components are moved toward the object side.

[0072] Hereinafter, conditions which are to be satisfied by the zoomlens systems of the embodiments will be described. It is not required tosimultaneously satisfy all of the following conditions.

[0073] Preferably, the zoom lens system of the invention satisfy thecondition defined by the following range of conditional expression (1):

3.0<f 1/fW<9.0  (1)

[0074] where

[0075] f1 represents a focal length of the first lens unit,

[0076] fW represents a focal length of the whole system at the shortestfocal length condition.

[0077] The above conditional expression (1) defines the focal length ofthe first lens unit. When the upper limit of range of conditionalexpression (1) is exceeded, the focal length of the first lens unitincreases excessively, so that the movement amount of the first lensunit in a zooming operation from the shortest focal length condition tothe longest focal length condition increases. Therefore, the totallength of the zoom lens system at the longest focal length conditionincreases, with the result that a compact zoom lens system cannot beobtained. By contrast, when the lower limit of range of conditionalexpression (1) is exceeded, the power of the first lens unit increasesexcessively, so that the aberration generated in the first lens unit,particularly the spherical aberration in the long focal length side,increases. As a result, the zoom lens system as a whole cannot attain anexcellent optical performance. Therefore, this is not preferable.

[0078] More preferably, with respect to the above condition, the rangesof conditional expressions (1a) to (1c), within the range of conditionalexpression (1), are satisfied in the following sequence:

3.5<f 1/fW<9.0  (1a)

4.5<f 1/fW<9.0  (1b)

5.0<f 1/fW<9.0  (1c)

[0079] wherein f1 and fW are defined supra.

[0080] Preferably, the zoom lens systems of the invention satisfy thecondition defined by the range of conditional expression(2):

−1.3<f 2/fW<−0.7  (2)

[0081] where

[0082] f2 represents a focal length of the second lens unit, and

[0083] fW is as defined supra.

[0084] The above conditional expression (2) defines the focal length ofthe second lens unit. When the value of f2/fW is less than the lowerlimit of the range of conditional expression (2), the focal length ofthe second lens unit decreases, so that the axial distance between thesecond and third lens units at the shortest focal length conditionincreases. Therefore, the total length at the shortest focal lengthcondition increases. As a result, the diameters of the lenses of thefirst and second lens units are enlarged. Therefore, this is notpreferable. By contrast, when the upper limit of the range ofconditional expression (2) is exceeded, the power of the second lensunit increases, so that the aberration generated in the first lens unit,particularly the Petzval sum, increases in the minus direction, therebycausing the Petzval sum of the whole system to be excessively large. Asa result, the whole system cannot obtain an excellent opticalperformance. Therefore, this is not preferable.

[0085] More preferably, with respect to the above conditional expression(2), the ranges of conditional expressions (2a) and (2b), within therange of conditional expression (2), are satisfied in the followingsequence:

−1.3<f 2/fW<−0.8  (2a)

−1.4<f 2/fW<−0.8  (2b)

[0086] wherein f2 and fW are as defined supra.

[0087] Preferably, the zoom lens systems of the invention satisfy thecondition defined by the range of the following conditional expression(3):

1.1<f 3/fW<1.8  (3)

[0088] where

[0089] f3 represents a focal length of the third lens unit, and

[0090] fW is as defined supra.

[0091] The above conditional expression (3) defines the focal length ofthe third lens unit. When the upper limit of range of conditionalexpression (3) is exceeded, the focal length of the third lens unitincreases excessively. Therefore, the total length at the longest focallength condition becomes too long, with the result that a compact zoomlens system cannot be obtained. By contrast, when the value of f3/fW isless than the lower limit of the range of conditional expression (3),the power of the third lens unit increases, so that the aberrationgenerated in the third lens unit, particularly a coma aberration,increases. The coma aberration cannot be corrected even by forming anaspherical surface at any place in a zoom lens system. As a result, thewhole system cannot attain an excellent optical performance. Therefore,this is not preferable.

[0092] More preferably, with respect to the above conditional expression(3), the following conditional expression (3a), within the range ofconditional expression (3), is satisfied:

1.8<f 3/fW<1.9  (3a)

[0093] Preferably, the zoom lens systems of the invention satisfy thecondition defined by the range of the following conditional expression(4):

1.0<img*R<15.0  (4)

[0094] where

[0095] img represents a maximum image height (the unit is mm), and

[0096] R represents an effective diameter (the unit is mm) of the lenssurface which is closest to the image side among the lens surfaces(excluding the filter and the like) constituting the zoom lens system.

[0097] The above conditional expression (4) is set in order to balancethe conditions on the degree of the zoom lens diameter and theaberration corrections, with those peculiar to an imaging optical systemof a digital camera. In an imaging optical system of a digital camerausing a solid state imaging device, in order to sufficiently satisfy thefocal property of a microlens disposed in front of the solid stateimaging device, the light flux must generally be incident with an anglewhich is substantially perpendicular to the light flux of the microlens.Therefore, it is desirable that an imaging optical system of a digitalcamera correct aberrations in the same manner as that of a conventionalcamera using a silver halide film, and also be approximately telecentricwith respect to the image side. When the upper limit of the range ofconditional expression (4) is exceeded in the zoom lens system, theapproximate telecentric state with respect to the image side becomesstronger than required, and aberrations, particularly, a negativedistortion aberration in the short focal length side, increaseexcessively. As a result, the aberrations are hardly corrected and theimage plane is largely curved toward the under side. Therefore, this isnot preferable. By contrast, when the value of img*R is less than thelower limit of range of conditional expression (4), it is difficult tosatisfy the approximate telecentric state, and hence this is notpreferable. When the telecentricity is to be improved under the statewhere the value img*R is less than the lower limit, the back focus ofthe zoom lens system is larger than required, thereby causing the sizeof the optical system to be increased. Therefore, this is notpreferable.

[0098] More preferably, with respect to the above conditional expression(4), the range of the following conditional expression (4a), within therange of the conditional expression (4), is satisfied:

6.5<img*R<9.5  (4a)

[0099] In a zoom lens system which is configured along the optical axisin the sequence from the object side by a first lens unit havingpositive optical power, a second lens unit having negative opticalpower, and a third lens unit having positive optical power in the samemanner as the zoom lens systems of the embodiments, the third lens unitpreferably comprises a positive lens component including the positivelens element which is closest to the image side and which has a strongcurvature face, and a negative lens component formed by at least onenegative lens element. According to this configuration, aberrations canbe satisfactorily corrected.

[0100] With respect to the positive lens element which is closest to theobject side among the lens elements of the third lens unit, thecondition defined by the range of the following conditional expression(5) is preferably satisfied:

0.1<Ra/f 3<3.0  (5)

[0101] where

[0102] Ra represents a radius of curvature of the object side-face ofthe positive lens element which is closest to the object side among thelens elements of the third lens unit, and

[0103] f3 represents a focal length of the third lens unit.

[0104] The above condition defines a ratio of the radius of curvature,of the object side-face of the positive lens element which is closest tothe object side among the lens elements of the third lens unit, to thefocal length of the third lens unit, and relates to the aberrationcorrecting power of the positive lens element. When the upper limit ofthe range of conditional expression (5) is exceeded, the curvature ofthe positive lens element becomes too weak, and the tendency of aspherical aberration to vary toward the overside is increased.Therefore, this is not preferable. By contrast, when the value of Ra/f3is less than the lower limit of the range of conditional expression (5),the curvature of the positive lens element becomes too strong, and thetendency of a spherical aberration to vary toward the underside isincreased. Therefore, this is not preferable. Moreover, when the valueof Ra/f3 is less than the lower limit of the range of conditionalexpression (5), the radius of curvature of the object side-face of thepositive lens element is reduced excessively, and hence it is difficultto produce the positive lens element. Therefore, this is not preferable.

[0105] In a zoom lens system which is configured along the optical axisin the sequence from the object side by a first lens unit havingpositive optical power, a second lens unit having negative opticalpower, and a third lens unit having positive optical power in the samemanner as the zoom lens systems of the embodiments, the second lens unitis preferably configured along the optical axis in the sequence from theobject side by: a first sub-unit of the second lens unit, including alens element in which a concave face of a stronger curvature is directedtoward the image side; and a second sub-unit of the second lens unit,including at least one positive lens element on the object side, and onenegative lens element. In the case where the second lens unit isconfigured in this way, when light beams are emitted from the concaveface of stronger curvature in the first sub-unit of the second lensunit, the emission angles of the off-axis beams and the axial beams arereduced, particularly in the short focal length side, so that aberrationcorrections of the second sub-unit of the second lens unit and thesubsequent lens unit can be facilitated.

[0106] With respect to the concave face in the first sub-unit of thesecond lens unit, the condition defined by the range of the followingconditional expression (6) is preferably satisfied:

−1.6<R 2 n/f 2<−0.6  (6)

[0107] where

[0108] R2n represents a radius of curvature of the concave face in thefirst sub-unit of the second lens unit, and

[0109] f2 represents a focal length of the second lens unit.

[0110] The above conditional expression (6) defines a ratio of theradius of curvature, of the concave face of stronger curvature in thefirst sub-unit of the second lens unit, to the focal length of thesecond lens unit, and relates to the aberration correcting power of theconcave face. When the value of R2n/f2 is less than the lower limit ofrange of conditional expression (6), the curvature of the concave facebecomes too weak, and the above-mentioned function, i.e., the functionof reducing the emission angles of off-axis beams and axial beams whenlight beams incident on the concave face are emitted from the concaveface cannot be sufficiently attained. As a result, when the value ofR2n/f2 is less than the lower limit of the range of conditionalexpression (6), light beams to be emitted from the first sub-unit of thesecond lens unit are emitted to the subsequent unit while maintainingthe large angle between the off-axis beams and the axial beams, andaberrations in the image plane, particularly a curvature of field and acoma aberration, cannot be corrected in the subsequent unit. Therefore,this is not preferable. By contrast, when the upper limit of the rangeof conditional expression (6) is exceeded, the curvature of the concaveface becomes too strong, so that a very large aberration is singlygenerated in the concave face. The aberration cannot be corrected inanother face. Therefore, this is not preferable. Moreover, when theupper limit of the range of conditional expression (6) is exceeded, theradius of curvature of the concave face is reduced excessively, andhence it is difficult to produce such a concave face. Therefore, this isnot preferable.

[0111] Preferably, the second sub-unit of the second lens unit isconfigured along the optical axis in the sequence from the object sideby: a bi-convex positive single, lens element; and a doublet lenselement composed of a positive lens element having a convex face on itsimage side, and a bi-concave negative lens element. The second lens unithas a negative optical power as a whole. However, in the case where achromatic aberration is to be corrected in the second lens unit, onepositive lens element and at least one negative lens element must beincluded at least in the second lens unit. On the other hand, since theconcave face of stronger curvature on the image side exists in the firstsub-unit of the second lens unit as described above, a positive lenselement of a high power for correcting the chromatic aberrationgenerated in the concave face cannot be used in the first sub-unit ofthe second lens unit. In order to correct chromatic aberration of thewhole second lens unit, the second sub-unit of the second lens unit ispreferably configured along the optical axis by: a bi-convex positivesingle lens element; and a doublet lens element composed of a positivelens element having a convex face on its image side, and a bi-concavenegative lens element.

[0112] With respect to the positive lens element of the second sub-unitof the second lens unit, the condition defined by following range ofconditional expression (6)′ is satisfied.

−2.5<f 2 p/f 2<−1.0  (6)′

[0113] where

[0114] f2p represents a focal length of the positive lens element of thesecond sub-unit of the second lens unit,

[0115] f2 represents a focal length of the second lens unit.

[0116] The above conditional expression (6)′ defines a ratio of thefocal length, of the positive lens element of the second sub-unit of thesecond lens unit, to the focal length of the second lens unit, andrelates to the correction of a chromatic aberration of the second lensunit. When the value f2p/f2 is less than the lower limit of the range ofconditional expression (6)′, the power of the positive lens elementbecomes too weak, and a chromatic aberration, generated in the secondlens unit, is increased. Therefore, this is not preferable. By contrast,when the upper limit of the range of conditional expression (6)′ isexceeded, the power of the positive lens element becomes too strong, sothat, in order to correct the chromatic aberration of the second lensunit, the power of the negative lens included in the second lens unitmust be enhanced. As a result, although the chromatic aberration can becorrected, it is difficult to correct a usual monochromatic aberration.Therefore, this is not preferable.

[0117] In the zoom lens systems of the invention, the first lens unitcomprises in the sequence along the optical axis from the object side: anegative lens element having a convex face on its image side, abi-convex positive lens element, and a positive lens element having aconvex face on its object side. In order to correct a chromaticaberration in the first lens unit, at least one positive lens elementand at least one negative lens element must be disposed in the firstlens unit. However, when the first lens unit having a positive opticalpower as a whole is configured by using only one positive lens elementand one negative lens element, it is difficult to correct an aberrationin the long focal length side, particularly a spherical aberration. Inorder to correct a spherical aberration of high order in the long focallength side, the first lens unit, in which the axial beams pass at ahigh beam height, is preferably provided with a degree of freedom indesign (the number of lens elements) for further aberration correction.Moreover, when the first lens unit is configured by using only onepositive lens element and one negative lens element, it is difficult tocorrect a chromatic aberration in the range of optical constants ofexisting glass and plastics.

[0118] In the case where the first lens unit is configured along theoptical axis in the sequence from the object side by: a negative lenselement having a convex face on its image side, a bi-convex positivelens element, and a positive lens element having a convex face on itsobject side as described above, the conditions defined by the ranges ofthe following conditional expressions (7) and (8) are preferablysatisfied:

νn<35  (7)

νp>50  (8)

[0119] where

[0120] νn represents an Abbe number of the negative lens element of thefirst lens unit, and

[0121] νp represents an Abbe number of each positive lens element of thefirst lens unit.

[0122] The above conditional expressions (7) and (8) relate to thecorrection of a chromatic aberration in the first lens unit. When theAbbe numbers of the one negative lens element and the two positive lenselements of the first lens unit are adequately defined, a chromaticaberration in the first lens unit can be satisfactorily corrected.

[0123] With respect to the conditional expression (7), when thefollowing ranges of conditional expression are further satisfied, achromatic aberration can be more satisfactorily corrected.

νn<32  (7a)

νn<30  (7b)

[0124] The zoom lens system of each of the embodiments is configured sothat, in a zooming operation from the shortest focal length condition tothe longest focal length condition, the first lens unit is moved towardthe object side. According to this configuration, the total length ofthe zoom lens system at the shortest focal length condition can be madeshort, and the diameters of the lens elements constituting the firstlens unit can be reduced. Therefore, this configuration is preferable.

[0125] When, in a zooming operation from the shortest focal lengthcondition to the longest focal length condition, the first lens unit isto be moved toward the object side as described above, the conditiondefined by the range of the following conditional expression (9) ispreferably satisfied:

0.7<m 1/Z<3.0  (9)

[0126] where

[0127] m1 represents a movement amount (mm) of the first lens unit inthe zooming operation from the shortest focal length condition to thelongest focal length condition, and

[0128] Z represents a zoom ratio (Z=fT/fW: ratio of the focal length atthe shortest focal length condition to that of the longest focal lengthcondition).

[0129] The above conditional expression (9) shows the relationshipbetween the movement amount of the first lens unit, in the zoomingoperation from the shortest focal length condition to the longest focallength condition, and the zoom ratio. Usually, as the zoom ratio ishigher, the movement amount is larger. Conditional expression (9)defines the condition for adequately defining the movement amount of thefirst lens unit, so that a zoom lens which is compact and which has anexcellent optical performance is provided. When the upper limit of theconditional expression (9) is exceeded, the movement amount of the firstlens unit becomes too large as compared with the zoom ratio. Therefore,the total length of the zoom lens system at the longest focal lengthcondition increases excessively, with the result that a compact zoomlens system cannot be obtained. By contrast, when the value m1/Z is lessthan the lower limit of the range of conditional expression (9), themovement amount of the first lens unit becomes too small. When themovement amount of the first lens unit is small, the zoom ratio cannotbe attained unless the power of the first lens unit is made larger. As aresult, the power of the first lens unit increases excessively, so thatthe degree of an aberration generated in the first lens unit increases.As a result, the zoom lens system as a whole cannot attain excellentoptical performance.

[0130] More preferably, with respect to the above condition (9), morepreferably, the condition defined by the range of the followingconditional expression (9a), within the range of conditional expression(9), is satisfied.

0.8<m 1/Z<3.0  (9a)

[0131] When, in a zooming operation from the shortest focal lengthcondition to the longest focal length condition, the first lens unit isto be moved toward the object side as described above, the conditiondefined by the range of the following conditional expression (10) ispreferably satisfied.

0.8<M 1 WM/M 1 MT<2.5  (10)

[0132] where

[0133] M1WM represents a movement amount of the first lens unit from theshortest focal length condition to the middle focal length condition,and

[0134] M1MT represents a movement amount of the first lens unit from themiddle focal length condition to the longest focal length condition, themiddle focal length being a focal length which is (fW*fT )^(1/2) wherefW is the focal length of the entire zoom lens system at the shortestfocal length condition and fT is the focal length of the entire zoomlens system at the longest focal length condition.

[0135] The above conditional expression (10) defines a ratio of themovement amount of the first lens unit, from the shortest focal lengthcondition to the middle focal length condition, to that from the middlefocal length condition to the longest focal length condition, and showsthat the variation of the movement amount of the first lens unit in thechange from the shortest focal length condition to the middle focallength condition is larger than that in the change from the middle focallength condition to the longest focal length condition. In particular,when the movement amount of the first lens unit from the shortest focallength condition to the middle focal length condition is set to berelatively large, the position of the entrance pupil in the range of themiddle focal length can be made remote from the image plane, and theflare component of off-axis beams can be moved away.

[0136] More preferably, with respect to the above condition, thecondition defined by the ranges of the following conditional expressions(10a) and (10b), within the range of conditional expression (10), aresatisfied:

0.9<M 1 WM/M 1 MT<2.5  (10a)

1.2<M 1 WM/M 1 MT<2.2  (10b)

[0137] Preferably, the zoom lens systems of the embodiments satisfy thecondition defined by the range of the following conditional expression(11):

1<max(T 1, T 2, T 3)/fW<4  (11)

[0138] where

[0139] Ti is the axial thickness of an i-th unit and max(T1, T2, T3)isthe maximum value of the thickness.

[0140] The above conditional expression (11) is set in order to attain azoom lens system which is small in size and which has a highmagnification. When the value of max(T1, T2, T3)/fW is less than thelower limit of the range of conditional expression (11), the axialthicknesses of the lens units become too small, and it is difficult toensure working requirements (the center thickness, the edge thickness,and the like) of the lens elements constituting the lens units.Furthermore, the degree of freedom in design required for the correctionof an aberration cannot be ensured. By contrast, when the upper limit ofrange of conditional expression (11) is exceeded, the axial thicknessesof the lens units become too large, and a compact zoom lens systemcannot be attained.

[0141] More preferably, with respect to the above condition, thecondition defined by the range of the following conditional expression(11a), within the range of conditional expression (11), is satisfied:

1<max(T 1, T 2, T 3)/fW<3  (11a)

[0142] Preferably, the zoom lens systems of the embodiments satisfy thecondition defined by the range of the following conditional expression(12):

6<Lw/fW<10  (12)

[0143] where

[0144] Lw represents the total length of the optical system at theshortest focal length condition (the length from the tip end of the lenselement to the image plane), and fW is as defined supra.

[0145] The above conditional expression (12) indicates the telephotoratio at the shortest focal length condition. When the value of Lw/fW isless than the lower limit of the range of conditional expression (12),the total length of the optical system becomes too short, and it isdifficult to correct an aberration. Furthermore, it is difficult tosatisfy the approximate telecentric condition required for an imagingoptical system of a digital camera. By contrast, when the upper limit ofthe range of conditional expression (12) is exceeded, the compaction ofthe zoom lens system cannot be attained. When the total length isincreased, the illumination in the image plane cannot be ensured,thereby requiring the diameter of the front lens to be increased. Alsoin this case, therefore, a compact zoom lens system cannot be attained.

[0146] In a zoom lens system, the focal length is varied by changing thedistances between lens units, or, in other words, the variablemagnification amount (β) of each unit. Therefore, a lens unit in whichthe variable magnification amount is largely changed as a result of azooming operation contributes to magnification at a higher degree, andhence inevitably bears a large portion of an aberration. In view ofthis, in order to efficiently perform a zooming operation, units of azoom lens system preferably bear variable magnification in a manner asuniform as possible. Realization of such a relationship of the burdensof variable magnification results in the lens units also bearing anaberration in a uniform manner. In this case, it is seemed that theconfiguration (the number and size of components) of each lens unit ofthe zoom lens system is optimized.

[0147] In view of the above, preferably, the zoom lens systems of theinvention satisfy the condition defined by the range of the followingconditional expression (13):

0.2<Δβ3/Δβ2<1.0  (13)

[0148] where

[0149] Δβ2 represents the ratio of lateral magnifications (the lateralmagnification at the longest focal length condition/the lateralmagnification at the shortest focal length condition) of the second lensunit, and

[0150] Δβ3 represents the ratio of lateral magnifications (the lateralmagnification at the longest focal length condition/the lateralmagnification at the shortest focal length condition) of the third lensunit.

[0151] The above conditional expression (13) indicates the burdens ofvariable magnification of the second and third lens units. Unlike a zoomlens system which is known in the prior art and in which the second lensunit bears a large portion of the variable magnification, the third lensunit also bears variable magnification, thereby allowing a zoomingoperation to be efficiently performed. As a result, the optical systemis shortened, and the lens units are simplified in configuration. Whenthe value Δβ3/Δβ2 is less than the lower limit of the range ofconditional expression (13), the burden of variable magnification of thethird lens unit decreases and that of the second lens unit increases,and hence spherical aberration in the long focal length side inclines tothe underside and also a distortion aberration in the short focal lengthside increases, with the result that the aberration correction cannot beperformed. By contrast, when the upper limit of range of conditionalexpression (13) is exceeded, the burden of variable magnification of thethird lens unit increases. Therefore, a spherical aberration in the longfocal length side varies to the overside, an off-axis coma aberration isgenerated in both the long and short focal length sides, and theaberration correction cannot be performed by the other components. Inboth cases, when the configuration is used as it is, the aberrationcorrection cannot be sufficiently performed, and an increase of thedegree of freedom in design inevitably causes the number of componentsto be increased and the size of the lens system to be enlarged.

[0152] More preferably, with respect to the above conditional expression(13), the condition defined by the ranges of the following conditionalexpressions (13a) to (13c) within the range of conditional expression(13) are satisfied:

0.25<Δβ3/Δβ2<1.0  (13a)

0.5<Δβ3/Δβ2<1.0  (13b)

0.7<Δβ3/Δβ2<1.0  (13c)

[0153] Preferably, the zoom lens systems of the invention satisfy thecondition defined by the range of the following conditional expression(14):

3.5<βT 2/βw 2<6.5  (14)

[0154] where

[0155] βT2 represents a lateral magnification of the second lens unit atthe longest focal length condition, and

[0156] βw2 represents a lateral magnification of the second lens unit atthe shortest focal length condition.

[0157] The above conditional expression (14) defines the change of thelateral magnification of the second lens unit in variable magnification,and more specifically defines the burden of variable magnification ofthe second lens unit. When the upper limit of the range of conditionalexpression (14) is exceeded, the burden of the variable magnification ofthe second lens unit becomes too large, and hence a spherical aberrationin the long focal length side inclines to the underside, and also adistortion aberration in the short focal length side increases, with theresult that the aberration correction cannot be performed. By contrast,when the value βT2/βw2 is less than the lower limit of the range ofconditional expression (14), the burden of variable magnification of thesecond lens unit decreases, and the burdens of the other lens unitsincrease. Therefore, a spherical aberration in the long focal lengthside varies to the overside, and an off-axis coma aberration increasesin both the long and short focal length sides. Consequently, this is notpreferable.

[0158] Preferably, the zoom lens systems of the invention satisfy thecondition defined by the range of the following conditional expression(15):

4.5<fT/|f 12 W|<15  (15)

[0159] where

[0160] fT represents a focal length at the longest focal lengthcondition, and

[0161] f12W represents a composite focal length of the first and secondlens units at the shortest focal length condition.

[0162] The above conditional expression (15) defines the composite focallength of the first and second lens units at the longest focal lengthcondition, and is set in order to obtain a small-sized lens system of ahigh magnification. When the value of fT/|f12W| is less than the lowerlimit of the range of conditional expression (15), the composite focallength of the first and second lens units in the short focal length sidebecomes too large, and it is difficult to ensure the back focus.Furthermore, the power of the first lens unit or the second lens unitbecomes too weak, and a compact zoom lens system cannot be attained. Bycontrast, when the upper limit of range of conditional expression (15)is exceeded, the composite focal length of the first and second lensunits in the short focal length side becomes too small, and it isdifficult to correct a distortion aberration in the short focal lengthside. Furthermore, the power of the first lens unit or the second lensunit becomes too strong, and hence it is difficult to correct anaberration. Therefore, this is not preferable.

[0163] In the zoom lens systems of the invention, the second lens unitpreferably has at least one aspherical surface which satisfies thecondition defined by the range of the following conditional expression(1):

−0.1<ø*(N′−N)*d/dH{X(H)−X 0(H)}<0  (16)

[0164] where

[0165] ø represents a power of a lens element having an asphericalsurface,

[0166] N represents a refractive index of a medium which is on theobject side with respect to the aspherical surface, to the d line,

[0167] N′ represents a refractive index of a medium which is on theimage side with respect to the aspherical surface, to the d line,

[0168] H represents a height in a direction perpendicular to the opticalaxis,

[0169] X(H) represents a displacement amount at the height H of theaspherical surface along the optical axis, and

[0170] X0(H) represents a displacement amount at the height H of areference spherical surface along the optical axis.

[0171] Among aspherical surfaces in the second lens unit, an asphericalsurface which is disposed so as to be relatively closer to the object iseffective in the correction of a distortion aberration in the shortfocal length side, and that which is disposed so as to be relativelycloser to the image is effective in the correction of a sphericalaberration in the long focal length side. The aspherical surfaces areset so as to function in a direction along which the power of theparaxial becomes weak, and the configuration consisting of only theaspherical surfaces serves to weaken an aberration which has beenexcessively corrected. In the embodiments, when the power of anaspherical surface of a negative face disposed in a lens element whichis in the second lens unit and closer to the object is too strong, anegative distortion aberration in the short focal length side becomestoo large. By contrast, when the negative power becomes weak, thecorrection of a distortion aberration in the short focal length side isadvantageously performed, but an aspherical aberration in the long focallength side is insufficiently corrected, with the result that theoptical performance cannot be ensured. Also when a positive power facein the second lens unit has an aspherical surface, similar phenomenaoccur in both the cases where the power of a positive face in the secondlens unit becomes weak, and where the negative optical power becomesstrong. When the power of an aspherical surface disposed in a positiveface of a lens which is in the second lens unit and relatively closer tothe image becomes too weak, a spherical aberration in the long focallength side varies to the overside, and the correction of a sphericalaberration is excessively performed. By contrast, when the power becomestoo strong, the correction is insufficient. Therefore, both cases arenot preferable.

[0172] In the zoom lens systems of the invention, the third lens unitpreferably has at least one aspherical surface which satisfies thecondition defined by the range of the following conditional expression(17):

−0.1<ø*(N′−N)*d/dH{X(H)−X 0(H)}<0  (17)

[0173] where

[0174] ø represents a power of a lens element having an asphericalsurface,

[0175] N represents a refractive index of a medium which is on theobject side with respect to the aspherical surface, to the d line,

[0176] N′ represents a refractive index of a medium which is on theimage side with respect to the aspherical surface, to the d line,

[0177] H represents a height in a direction perpendicular to the opticalaxis,

[0178] X(H) represents a displacement amount at the height H of theaspherical surface along the optical axis, and

[0179] X0(H) represents a displacement amount at the height H of areference spherical surface along the optical axis.

[0180] Among aspherical surfaces in the third lens unit, an asphericalsurface which is disposed so as to be relatively closer to the object iseffective in the correction of a spherical aberration in the short focallength side, and a lens surface which is disposed so as to be relativelycloser to the image plane is effective in the correction of the imageplane performance and flare in the long focal length side. In the thirdlens unit, when an aspherical surface is disposed in a direction alongwhich the positive optical power of a lens element closer to the objectis weakened, in the case where the power becomes too weak, a sphericalaberration in the short focal length side is insufficiently corrected,and, in the case where the power becomes too strong, a sphericalaberration is excessively corrected. In both cases, when nocountermeasure is taken, it is difficult to correct an aberration in thesubsequent optical system. As a result, aberration correction inevitablycauses the number of components to be increased, or the size of the lenssystem to be enlarged. With respect to an aspherical surface disposed ina lens element in the third lens unit closer to the image plane and in adirection along which the negative optical power is weakened, when thenegative optical power becomes too weak, the convergency of the upperside for off-axis beams in the long focal length side is impaired andexcessive flare is produced, with the result that the image planeperformance is lowered. In the short focal length side, the off-axisbeams are extremely affected, and an excessive negative distortionaberration is generated. By contrast, when the negative optical powerbecomes too strong, the off-axis beams in the short focal length sideare affected, and the image plane performance in the short focal lengthside is lowered. Specifically, the off-axis image plane in the shortfocal length side is curved toward the positive direction and also anaberration cannot be sufficiently corrected in the other faces.

[0181] In the invention, the diaphragm is preferably kept stationary ina zooming operation. When the diaphragm is to be moved, a space must beensured for a cam device for moving the diaphragm, a lens barrel, a camdriving device, and the like, so that the size of an optical apparatusinto which the zoom lens system is incorporated is enlarged.

[0182] In the embodiments, the diaphragm is preferably disposed betweenthe second and third lens units. The disposition of the diaphragmbetween the second and third lens units can prevent the quantity ofperipheral light from being lowered in a zooming operation from theshortest focal length condition to the middle focal length condition.

[0183] Preferably, the full aperture is constant in a zooming operation.Usually, the diaphragm functions by means of an operation of opening orclosing diaphragm vanes with respect to a circular opening correspondingto the full FNO. In view of an influence on the image, the opening ofthe full aperture is preferably circular. In view of an influence on theimage, when the full aperture at each focal length condition varies in azooming operation, the diaphragm must be controlled in accordance withthe configuration in which the circular opening is formed by diaphragmvanes or in which plural circular openings are disposed. In the formerconfiguration using diaphragm vanes, when the number of the diaphragmvanes is small, the opening has a distorted shape. In order to make theopening close to be circular, a large number of, for example, five orsix vanes are required, whereby the production cost is inevitablyincreased. In the latter configuration using plural circular openings,the production cost is increased, and a space for inserting the circularopenings along the optical axis is necessary, with the result that thesize of the optical system is enlarged.

[0184] Hereinafter, specific examples of the embodiments will bedescribed with reference to construction data, aberration diagrams, etc.

[0185] Embodiments 1 to 9, which will be described, correspond to theembodiments described above, with respect to FIGS. 1-9, respectively.The lens arrangement diagrams showing the embodiments indicate the lensconfigurations of the corresponding Embodiments 1 to 9, respectively.

[0186] In the embodiments, ri (i=1, 2, 3 . . . indicates the radius ofcurvature of an i-th surface counted from the object side, di (i=1, 2, 3. . . indicates an i-th axial surface separation counted from the objectside, and Ni (i=1, 2, 3 . . . ) and vi (i=1, 2, 3 . . . ) indicate therefractive index and the Abbe number of an i-th lens element countedfrom the object side, to the d line. Furthermore, f indicates the focallength of the whole system, and FNO indicates the F number. The letter Eattached to the data of the embodiments indicates the exponential partof the corresponding value. For example, 1.0E-2 indicates 1.0*10⁻². Inthe first and second embodiments, the focal length f of the wholesystem, the F number FNO, and the air space (axial surface separation)between the lens units correspond, in the sequence from the left side,to the values at the shortest focal length end (wide angle end) (W), themiddle focal length (M), and the longest focal length end (telephotoend) (T), respectively.

[0187] In the embodiments, a surface in which the radius of curvature riis marked with “*” indicates a refractive optical surface having anaspherical shape, or a surface having a refractive action which isequivalent to an aspherical surface, and is defined by the followingexpression showing the shape of an aspherical surface.

X(H)=CH ²/{1−{square root}{square root over ( )}(1−ε*C ² *H²)}+ΣAi*Hi(AS)

[0188] where

[0189] H represents a height in direction perpendicular to the opticalaxis,

[0190] X(H) represents a displacement amount at the height H along theoptical axis (with respect to the surface vertex),

[0191] C represents a paraxial curvature,

[0192] ε represents a quadric surface parameter,

[0193] Ai represents a i-th order aspherical coefficient, and

[0194] Hi represents a symbol indicating an i-th power of H. TABLE 1[Embodiment 1] f = 5.10˜16.00˜48.70 FNO = 2.87˜3.81˜4.10 Radius of AxialRefractive Abbe Curvature Distance Index Number r1 =  45.859 d1 =  0.60N1 = 1.848500 ν1 = 30.68 r2 =  20.428 d2 =  2.99 N2 = 1.487490 ν2 =70.44 r3 = −324.147 d3 =  0.10 r4 =  19.254 d4 =  2.07 N3 = 1.697209 ν3= 53.73 r5 =  60.367 d5 =  0.50˜12.25˜22.37 r6* =  20.403 d6 =  0.60 N4= 1.487490 ν4 = 70.44 r7* =   4.402 d7 =  3.41 r8 =  −4.856 d8 =  0.60N5 = 1.677393 ν5 = 54.61 r9 =   8.996 d9 =  0.94 N6 = 1.847540 ν6 =26.68 r10 =  −35.025 d10 =  9.11˜3.73˜0.50 r11 = ∞ d11 =  0.10 r12 =  4.931 d12 =  1.52 N7 = 1.688805 ν7 = 54.09 r13 =  276.773 d13 =  1.20r14* =  54.486 d14 =  1.55 N8 = 1.846943 ν8 = 24.67 r15* =   5.110 d15 = 0.12 r16 =   5.287 d16 =  1.71 N9 = 1.517549 ν9 = 53.54 r17 =  −15.384d17 =  3.03 r18* =  47.080 d18 =  4.94 N10 = 1.549950 ν10 = 43.56 r19* = −88.189 d19 =  0.50˜5.65˜7.24 r20 = ∞ d20 =  4.00 N11 = 1.516800 ν11 =64.20 r21 = ∞ [Aspherical Coefficient] r6 ε =  1.0000 A4 =  7.13888 *10⁻⁴ A6 =  3.37921 * 10⁻⁶ A8 =  1.72001 * 10⁻⁶ A10 = −1.22479 * 10⁻⁷ A12=  3.86499 * 10⁻⁹ r7 ε =  1.0000 A4 =  1.67098 * 10⁻⁴ A6 = −1.15883 *10⁻⁵ A8 =  2.22223 * 10⁻⁵ A10 = −3.12740 * 10⁻⁶ A12 =  1.79225 * 10⁻⁷r14 ε =  1.0000 A4 = −1.69606 * 10⁻³ A6 =  2.67616 * 10⁻⁵ A8 =−2.23107 * 10⁻⁶ A10 =  3.32446 * 10⁻⁸ A12 =  2.70875 * 10⁻⁹ r15 ε = 1.0000 A4 =  2.90840 * 10⁻⁴ A6 =  5.95412 * 10⁻⁵ A8 =  1.21372 * 10⁻⁵A10 = −4.45671 * 10⁻⁷ A12 = −1.32895 * 10⁻¹⁶ r18 ε =  1.0000 A4 =−4.29878 * 10⁻⁴ A6 = −5.56594 * 10⁻⁶ A8 =  1.05178 * 10⁻⁶ A10 = 4.77499 * 10⁻⁸ A12 = −7.26795 * 10⁻⁹ r19 ε =  1.0000 A4 = −6.14789 *10⁻⁴ A6 =  1.30569 * 10⁻⁶ A8 = −1.21935 * 10⁻⁷ A10 = −1.72881 * 10⁻⁸ A12= −3.48285 * 10⁻¹¹

[0195] TABLE 2 [Embodiment 2] f = 5.13˜15.50˜48.75 FNO = 2.73˜4.31˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 54.715 d1 =  0.60 N1 = 1.848322 ν1 = 29.85 r2 =  18.426 d2 =  0.30 r3 = 19.039 d3 =  3.49 N2 = 1.723013 ν2 = 52.69 r4 =  212.770 d4 =  0.10 r5=  18.135 d5 =  2.04 N3 = 1.705118 ν3 = 53.40 r6 =  39.130 d6 = 0.10˜11.45˜21.02 r7 =  10.006 d7 =  0.64 N4 = 1.599814 ν4 = 47.31 r8 =  4.127 d8 =  2.89 r9 =  17.521 d9 =  1.53 N5 = 1.798500 ν5 = 22.60 r10=  −17.604 d10 =  0.24 r11* =  −47.805 d11 =  1.34 N6 = 1.690894 ν6 =27.09 r12 =  −5.201 d12 =  0.60 N7 = 1.849789 ν7 = 38.39 r13* =   6.890d13 =  7.01˜2.76˜0.38 r14 = ∞ d14 =  3.00˜2.00˜0.10 r15* =   3.838 d15 = 2.26 N8 = 1.487490 ν8 = 70.44 r16 =  −38.408 d16 =  0.25 r17 =  10.795d17 =  1.97 N9 = 1.487490 ν9 = 70.44 r18 =  −7.048 d18 =  0.14 r19 = −6.196 d19 =  2.72 N10 = 1.846738 ν10 = 24.05 r20* =  −21.321 d20 = 0.11 r21 = −121.777 d21 =  3.77 N11 = 1.524957 ν11 = 61.87 r22* = 14.361 d22 =  0.20˜3.32˜4.91 r23 = ∞ d23 =  3.70 N12 = 1.516800 ν12 =64.20 r24 = ∞ [Aspherical Coefficient] r11 ε =  1.0000 A4 = −1.61599 *10⁻³ A6 =  5.40149 * 10⁻⁵ A8 =  1.17127 * 10⁻⁵ A10 = −1.31580 * 10⁻⁶ A12=  5.77527 * 10⁻⁸ r13 ε = 1.0000 A4 = −3.25983 * 10⁻³ A6 =  4.40857 *10⁻⁵ A8 =  2.32214 * 10⁻⁵ A10 = −3.63786 * 10⁻⁶ A12 =  2.01949 * 10⁻⁷r15 ε =  1.0000 A4 = −1.12778 * 10⁻³ A6 = −9.41601 * 10⁻⁵ A8 = 4.09453 * 10⁻⁶ A10 = −2.40382 * 10⁻⁷ A12 = −3.39204 * 10⁻⁸ r21 ε = 1.0000 A4 = −7.26725 * 10⁻³ A6 = −1.50172 * 10⁻⁴ A8 = −9.25368 * 10⁻⁵A10 =  9.06913 * 10⁻⁶ A12 = −1.04625 * 10⁻⁶ r22 ε =  1.0000 A4 =−4.56040 * 10⁻³ A6 = −1.54116 * 10⁻⁴ A8 =  6.72475 * 10⁻⁵ A10 =−1.14564 * 10⁻⁵ A12 =  7.09769 * 10⁻⁷

[0196] TABLE 3 [Embodiment 3] f = 5.13˜15.50˜48.75 FNO = 2.73˜4.31˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 56.851 d1 =  0.60 N1 = 1.839592 ν1 = 27.49 r2 =  23.446 d2 =  0.11 r3 = 23.446 d3 =  3.85 N2 = 1.567298 ν2 = 61.49 r4 = −317.865 d4 =  0.10 r5=  21.360 d5 =  2.74 N3 = 1.754500 ν3 = 51.57 r6 =  50.308 d6 = 0.10˜13.11˜23.02 r7 =  10.549 d7 =  0.60 N4 = 1.622384 ν4 = 38.80 r8 =  4.002 d8 =  2.00 r9 =  14.422 d9 =  1.35 N5 = 1.798500 ν5 = 22.60 r10=  −15.568 d10 =  0.10 r11* =  −22.319 d11 =  1.35 N6 = 1.681782 ν6 =27.64 r12 =  −4.598 d12 =  0.60 N7 = 1.850000 ν7 = 40.04 r13* =   7.695d13 =  7.73˜5.61˜1.19 r14 = ∞ d14 =  2.84˜0.20˜0.10 r15* =   3.880 d15 = 2.17 N8 = 1.487490 ν8 = 70.44 r16 =  −35.992 d16 =  0.33 r17 =   9.979d17 =  1.98 N9 = 1.487490 ν9 = 70.44 r18 =  −7.299 d18 =  0.15 r19 = −6.274 d19 =  2.67 N10 = 1.846836 ν10 = 24.34 r20 =  −22.235 d20 = 0.22 r21* =  −49.128 d21 =  3.47 N11 = 1.527547 ν11 = 63.51 r22* = 16.004 d22 =  0.52˜3.16˜3.25 r23 = ∞ d23 =  3.70 N12 = 1.516800 ν12 =64.20 r24 = ∞ [Aspherical Coefficient] r11 ε =  1.0000 A4 = −1.51649 *10⁻³ A6 =  2.66548 * 10⁻⁵ A8 =  1.22282 * 10⁻⁵ A10 = −1.32300 * 10⁻⁶ A12=  4.92614 * 10⁻⁸ r13 ε =  1.0000 A4 = −3.23885 * 10⁻³ A6 =  3.40371 *10⁻⁵ A8 =  2.06254 * 10⁻⁵ A10 = −3.68376 * 10⁻⁶ A12 =  2.02326 * 10⁻⁷r15 ε =  1.0000 A4 = −1.12558 * 10⁻³ A6 = −8.48960 * 10⁻⁵ A8 = 3.21273 * 10⁻⁶ A10 = −1.83274 * 10⁻⁷ A12 = −3.06639 * 10⁻⁸ r21 ε = 1.0000 A4 = −7.38365 * 10⁻³ A6 = −2.15053 * 10⁻⁴ A8 = −9.38824 * 10⁻⁵A10 =  9.96727 * 10⁻⁶ A12 = −1.04625 * 10⁻⁶ r22 ε =  1.0000 A4 =−3.78250 * 10⁻³ A6 = −2.14667 * 10⁻⁴ A8 =  6.93245 * 10⁻⁵ A10 =−1.13196 * 10⁻⁵ A12 =  7.18551 * 10⁻⁷

[0197] TABLE 4 [Embodiment 4] f = 5.10˜16.00˜48.69 FNO = 3.22˜4.10˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 =  30.563 d1 =  0.60 N1 = 1.818759 ν1 = 23.23 r2 =   14.423 d2 =  2.62 N2= 1.642484 ν2 = 56.38 r3 =  502.675 d3 =  0.10 r4 =   12.680 d4 =  1.71N3 = 1.754500 ν3 = 51.57 r5 =   32.327 d5 =  0.50˜5.68˜9.82 r6* =  31.105 d6 =  0.60 N4 = 1.713476 ν4 = 53.06 r7* =   4.594 d7 =  3.10 r8=   −4.932 d8 =  0.60 N5 = 1.697627 ν5 = 53.71 r9 =   8.955 d9 =  1.01N6 = 1.813453 ν6 = 22.98 r10 =  −25.524 d10 = 10.19˜4.78˜0.50 r11 = ∞d11 =  0.10 r12 =   4.921 d12 =  1.66 N7 = 1.676156 ν7 = 50.74 r13 = −95.562 d13 =  0.85 r14* =  −181.749 d14 =  1.16 N8 = 1.847905 ν8 =28.07 r15* =   5.217 d15 =  0.12 r16 =   5.230 d16 =  1.65 N9 = 1.495513ν9 = 64.74 r17 =   −9.579 d17 =  5.16 r18* = −4955.676 d18 =  3.36 N10 =1.807490 ν10 = 44.15 r19* =  136.647 d19 =  0.50˜5.55˜8.24 r20 = ∞ d20 = 3.40 N11 = 1.516800 ν11 = 64.20 r21 = ∞ [Aspherical Coefficient] r6 ε = 1.0000 A4 =  7.61844 * 10⁻⁴ A6 = −3.34498 * 10⁻⁵ A8 =  1.91322 * 10⁻⁶A10 = −3.06438 * 10⁻⁸ A12 =  1.77936 * 10⁻¹⁰ r7 ε =  1.0000 A4 = 5.09017 * 10⁻⁴ A6 = −4.07384 * 10⁻⁵ A8 =  1.60395 * 10⁻⁵ A10 =−2.56405 * 10⁻⁶ A12 =  1.79225 * 10⁻⁷ r14 ε =  1.0000 A4 = −1.63035 *10⁻³ A6 =  4.61794 * 10⁻⁵ A8 =  2.66015 * 10⁻⁶ A10 = −9.53202 * 10⁻⁸ A12= −2.86433 * 10⁻⁸ r15 ε =  1.0000 A4 =  2.43530 * 10⁻⁴ A6 =  7.95268 *10⁻⁵ A8 =  9.79297 * 10⁻⁶ A10 =  2.58484 * 10⁻⁷ A12 = −1.14984 * 10⁻⁷r18 ε =  1.0000 A4 = −9.11167 * 10⁻⁴ A6 = −2.73536 * 10⁻⁵ A8 = 2.88114 * 10⁻⁶ A10 =  9.33187 * 10⁻⁹ A12 = −5.33332 * 10⁻⁸ r19 ε = 1.0000 A4 = −1.03703 * 10⁻³ A6 =  1.21604 * 10⁻⁵ A8 = −5.10027 * 10⁻⁷A10 = −1.25593 * 10⁻⁷ A12 = −7.60189 * 10⁻¹⁰

[0198] TABLE 5 [Embodiment 5] f = 5.12˜15.50˜48.75 FNO = 2.73˜4.31˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 34.255 d1 =  0.60 N1 = 1.847049 ν1 = 25.00 r2 =  24.307 d2 =  0.16 r3 = 24.992 d3 =  3.41 N2 = 1.487490 ν2 = 70.44 r4 = −114.984 d4 =  0.10 r5=  20.927 d5 =  1.29 N3 = 1.565362 ν3 = 61.66 r6 =  31.362 d6 = 0.10˜12.78˜23.33 r7 =  17.176 d7 =  0.60 N4 = 1.847831 ν4 = 27.77 r8 =  5.655 d8 =  3.63 r9 =  22.850 d9 =  1.20 N5 = 1.798500 ν5 = 22.60 r10=  −13.011 d10 =  0.73 r11* =  −7.768 d11 = 0.75 N6 = 1.798500 ν6 =22.60 r12 =  −5.134 d12 =  0.60 N7 = 1.761352 ν7 = 50.41 r13* =  12.571d13 =  6.88˜2.11˜0.32 r14 = ∞ d14 =  3.00˜2.00˜0.10 r15 =   6.826 d15 = 1.12 N8 = 1.586416 ν8 = 59.98 r16 =  43.123 d16 =  0.10 r17 =   5.588d17 =  2.84 N9 = 1.517966 ν9 = 66.40 r18 =  −8.166 d18 =  0.35 r19 = −6.587 d19 =  1.09 N10 = 1.784209 ν10 = 29.06 r20 =   9.397 d20 =  1.80r21 =   3.568 d21 =  1.30 N11 = 1.531829 ν11 = 64.85 r22* =   8.075 d22=  3.19˜7.89˜12.83 r23 = ∞ d23 = 3.70 N12 = 1.516800 ν12 = 64.20 r24 = ∞[Aspherical Coefficient] r11 ε =  1.0000 A4 = −8.09441 * 10⁻⁴ A6 =−3.81431 * 10⁻⁵ A8 =  2.03843 * 10⁻⁵ A10 = −1.95474 * 10⁻⁶ A12 = 6.29809 * 10⁻⁸ r13 ε =  1.0000 A4 = −1.57384 * 10⁻³ A6 = −3.00291 *10⁻⁵ A8 =  2.34322 * 10⁻⁵ A10 = −2.90404 * 10⁻⁶ A12 =  1.29620 * 10⁻⁷r22 ε =  1.0000 A4 =  6.06134 * 10⁻³ A6 =  1.34200 * 10⁻⁵ A8 = 6.72379 * 10⁻⁵ A10 = −9.58951 * 10⁻⁶ A12 =  7.15528 * 10⁻⁷

[0199] TABLE 6 [Embodiment 6] f = 5.12˜15.50˜48.75 FNO = 2.26˜2.77˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 =  53.711 d1 =  0.60 N1 = 1.798500 ν1 = 22.60 r2 =   27.004 d2 =  3.20 N2= 1.754500 ν2 = 51.57 r3 = −1101.306 d3 =  0.10 r4 =   21.200 d4 =  1.97N3 = 1.487490 ν3 = 70.44 r5 =   38.384 d5 =  0.10˜13.58˜20.46 r6 =  10.109 d6 =  0.60 N4 = 1.849967 ν4 = 39.77 r7* =   5.358 d7 =  2.37 r8=  −64.671 d8 =  0.60 N5 = 1.850000 ν5 = 40.04 r9 =   8.081 d9 =  0.10r10 =   7.801 d10 =  1.90 N6 = 1.798500 ν6 = 22.60 r11 =  −16.817 d11 = 1.03 r12 =   −6.936 d12 =  0.60 N7 = 1.785779 ν7 = 46.80 r13* = 130.561 d13 =  9.15˜3.84˜0.11˜ r14 = ∞ d14 =  0.82˜0.89˜0.10 r15* =  8.023 d15 =  1.23 N8 = 1.674291 ν8 = 54.76 r16 =  −62.203 d16 =  0.10r17 =   5.569 d17 =  1.88 N9 = 1.487490 ν9 = 70.44 r18 =  −28.528 d18 = 0.10 r19 =   10.643 d19 =  0.60 N10 = 1.844735 ν10 = 23.77 r20 =  3.803 d20 =  3.07 r21 =   6.438 d21 =  4.05 N11 = 1.553618 ν11 = 42.71r22* =   17.611 d22 =  1.05˜4.20˜10.46 r23 = ∞ d23 =  3.70 N12 =1.516800 ν12 = 64.20 r24 = ∞ [Aspherical Coefficient] r7 ε =  1.0000 A4=  6.46463 * 10⁻⁶ A6 =  7.12987 * 10⁻⁶ A8 = −1.62410 * 10⁻⁶ A10 = 1.48107 * 10⁻⁷ A12 = −4.68558 * 10⁻⁹ r13 ε =  1.0000 A4 = −4.50773 *10⁻⁴ A6 =  1.11988 * 10⁻⁵ A8 = −1.26713 * 10⁻⁶ A10 =  7.63556 * 10⁻⁸ A12=  4.89912 * 10⁻¹⁰ r15 ε =  1.0000 A4 = −6.88311 * 10⁻⁴ A6 = −2.40885 *10⁻⁶ A8 = −1.07446 * 10⁻⁶ A10 =  1.21996 * 10⁻⁷ A12 = −5.39814 * 10⁻⁹r22 ε =  1.0000 A4 =  7.43446 * 10⁻⁴ A6 =  3.20186 * 10⁻⁵ A8 =−1.13515 * 10⁻⁵ A10 =  1.73213 * 10⁻⁶ A12 = −9.08995 * 10⁻⁸

[0200] TABLE 7 [Embodiment 2] f = 5.10˜16.01˜48.80 FNO = 3.10˜3.60˜4.20Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 51.316 d1 =  0.60 N1 = 1.818759 ν1 = 23.23 r2 =  21.286 d2 =  2.15 N2 =1.642484 ν2 = 56.38 r3 = −145.048 d3 =  0.10 r4 =  16.706 d4 =  1.36 N3= 1.754500 ν3 = 51.57 r5 =  35.177 d5 =  0.50˜7.83˜15.62 r6* =  24.341d6 =  0.60 N4 = 1.713476 ν4 = 53.06 r7* =   6.094 d7 =  3.72 r8 = −5.140 d8 =  0.22 N5 = 1.697627 ν5 = 53.71 r9 =   9.515 d9 =  0.75 N6 =1.813453 ν6 = 22.98 r10 =  −31.907 d10 = 10.45˜4.50˜0.40 r11 = ∞ d11 = 0.10 r12* =   4.781 d12 =  1.33 N7 = 1.727475 ν7 = 46.05 r13 =  −35.839d13 =  0.10 r14 =  239.202 d14 =  2.25 N8 = 1.755000 ν8 = 27.60 r15 =  4.906 d15 =  0.10 r16 =   5.581 d16 =  0.22 N9 = 1.747052 ν9 = 38.08r17 =   2.897 d17 =  1.40 N10 = 1.487000 ν10 = 70.40 r18 =  32.525 d18 = 0.84 r19* =   6.428 d19 =  0.69 N11 = 1.532956 ν11 = 51.14 r20 = 33.260 d20 =  1.38˜6.57˜5.88 r21 = ∞ d21 =  3.40 N12 = 1.516800 ν12 =64.20 r22 = ∞ [Aspherical Coefficient] r6 ε =  1.0000 A4 =  1.19413 *10⁻³ A6 = −5.05252 * 10⁻⁵ A8 =  2.33263 * 10⁻⁶ A10 = −7.39707 * 10⁻⁸ A12=  1.22559 * 10⁻⁹ r7 ε =  1.0000 A4 =  1.12929 * 10⁻³ A6 = −2.79368 *10⁻⁵ A8 =  2.71069 * 10⁻⁶ A10 = −2.07291 * 10⁻⁷ A12 =  5.55089 * 10⁻⁹r12 ε =  1.0000 A4 = −7.09501 * 10⁻⁴ A6 = −1.37096 * 10⁻⁵ A8 =−2.32713 * 10⁻⁶ A10 =  7.09276 * 10⁻⁸ r19 ε =  1.0000 A4 = −9.92974 *10⁻⁴ A6 =  1.23299 * 10⁻⁵ A8 =  1.61718 * 10⁻⁶ A10 =  3.97318 * 10⁻⁷

[0201] TABLE 8 [Embodiment 8] f = 5.10˜16.00˜49.00 FNO = 3.66˜3.39˜4.090Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 31.528 d1 =  0.70 N1 = 1.833500 ν1 = 21.00 r2 =  21.419 d2 =  0.55 r3 = 22.092 d3 =  3.72 N2 = 1.570699 ν2 = 61.21 r4 = −144.544 d4 =  0.08 r5=  16.481 d5 =  1.29 N3 = 1.487490 ν3 = 70.44 r6 =  28.275 d6 = 0.80˜11.02˜17.42 r7 =  14.115 d7 =  0.57 N4 = 1.771126 ν4 = 48.87 r8 =  5.297 d8 =  3.36 r9 =  −9.862 d9 =  0.30 N5 = 1.754500 ν5 = 51.57 r10=  10.625 d10 =  0.08 r11* =   8.323 d11 =  1.01 N6 = 1.846660 ν6 =23.82 r12* =  93.502 d12 = 10.85˜2.53˜0.90 r13 = ∞ d13 =  6.80˜6.40˜0.90r14 =   6.632 d14 =  1.10 N7 = 1.487490 ν7 = 70.44 r15 =  40.054 d15 = 0.08 r16 =   5.007 d16 =  2.29 N8 = 1.487490 ν8 = 70.44 r17 = −127.484d17 =  0.32 r18* =   6.494 d18 =  0.40 N9 = 1.846660 ν9 = 23.82 r19* =  3.815 d19 =  4.05˜7.35˜10.55 r20 = ∞ d20 =  7.19 N10 = 1.516800 ν10 =64.20 r21 = ∞ [Aspherical Coefficient] r11 ε =  1.0000 A4 = −2.70853 *10⁻⁴ A6 =  5.51414 * 10⁻⁵ A8 = −4.74840 * 10⁻⁶ r12 ε =  1.0000 A4 =−1.51231 * 10⁻⁴ A6 =  7.16807 * 10⁻⁵ A8 = −5.10893 * 10⁻⁶ r18 ε = 1.0000 A4 = −4.13231 * 10⁻³ A6 =  2.22876 * 10⁻⁴ A8 = −2.21116 * 10⁻⁵A10 =  7.83601 * 10⁻⁷ r19 ε =  1.0000 A4 = −3.12685 * 10⁻³ A6 = 2.80257 * 10⁻⁴ A8 = −1.80966 * 10⁻⁵ A10 =  2.22654 * 10⁻⁷

[0202] TABLE 9 [Embodiment 9] f = 5.12˜15.50˜48.74 FNO = 2.64˜3.60˜4.10Radius of Axial Refractive Abbe Curvature Distance Index Number r1 = 29.000 d1 =  0.60 N1 = 1.846920 ν1 = 24.60 r2 =  16.360 d2 =  4.84 N2 =1.596439 ν2 = 59.25 r3 = −62.939 d3 =  0.10 r4 =  13.488 d4 =  1.80 N3 =1.599568 ν3 = 59.03 r5 =  21.436 d5 =  1.02˜6.95˜12.11 r6 =  30.493 d6 = 0.60 N4 = 1.754500 ν4 = 51.57 r7* =  4.294 d7 =  2.36 r8 =  −4.433 d8 = 0.60 N5 = 1.582062 ν5 = 60.31 r9 =  10.934 d9 =  0.10 r10 =  11.027 d10=  0.94 N6 = 1.819163 ν6 = 23.13 r11 = −37.256 d11 =  8.65˜3.56˜0.10 r12= ∞ d12 =  0.10 r13* =  6.496 d13 =  1.42 N7 = 1.612875 ν7 = 58.14 r14 =−32.051 d14 =  1.18 r15 =  15.039 d15 =  1.86 N8 = 1.846758 ν8 = 24.11r16 =  5.085 d16 =  0.30 r17 =  6.436 d17 =  1.94 N9 = 1.487490 ν9 =70.44 r18* =  −8.524 d18 =  7.17˜5.52˜8.22 r19 = ∞ d19 =  7.19 N10 =1.516800 ν10 = 64.20 r20 = ∞ [Aspherical Coefficient] r7 ε =  1.0000 A4= −4.65301 * 10⁻⁴ A6 = −5.36672 * 10⁻⁵ A8 =  2.88202 * 10⁻⁵ A10 =−5.10403 * 10⁻⁶ A12 =  2.60914 * 10⁻⁷ r13 ε =  1.0000 A4 = −7.89688 *10⁻⁴ A6 = −3.19583 * 10⁻⁶ A8 =  5.47654 * 10⁻⁷ A10 = −6.96840 * 10⁻⁸ r18ε =  1.0000 A4 =  1.53515 * 10⁻⁴ A6 = −1.43399 * 10⁻⁵ A8 = −9.20984 *10⁻⁷ A10 =  1.03766 * 10⁻⁷ A12 = −2.46150 * 10⁻⁸

[0203] FIGS. 10 to 18 are aberration diagrams respectively correspondingto Embodiments 1 to 9 described above. In these figure descriptions, thesuffix (a), (b), or (c) indicates a diagram at the wide angle end, thesuffix (d), (e) or (f) indicates a diagram at the middle focal lengthcondition, and the suffix (g), (h) or (i) indicates a diagram at thetelephoto end. In the spherical aberration diagrams of the figures withthe suffix (a), (d), or (g), the solid line (d) indicates the d line,and the broken line (sc) indicates a sine condition. In the astigmatismdiagrams of the figures with the suffixes (b), (e), or (h), the solidline (DS) and the broken line (DM) indicate astigmatisms of the sagittalflux and the meridional flux, respectively. Furthermore, the figureswith the suffix (c), (f), or (i) are distortion aberration diagrams.Table 10 shows values corresponding to the conditional expressions inEmbodiments 1 to 9. TABLE 10 [Embodiment 1]  (1) f1/f1W: 7.30  (2)f2/f1W: −0.97  (3) f3/f1W: 1.60  (4) img * R: 8.1  (5) Ra/f3: 0.60  (6)R2n/f2: −0.89   (6)′ f2p/f2: —  (7) νn: 30.68  (8) νp: 70.44  (9) m1/Z:2.09 (10) M1WM/M1MT: 1.37 (11) max(T1,T2,T3)/f1W: 2.76 (12) Lw/f1W: 7.80(13) Δβ3/Δβ2: 0.447 (14) βT2/βw2: 4.62 (15) fT/|f12W|: 7.34 (16) φ * (N′− N) * d/dH{X(H) − X0(H)} r6 0.1 Hmax 0.3049E−05 0.2 Hmax 0.2457E−04 0.3Hmax 0.8438E−04 0.4 Hmax 0.2067E−03 0.5 Hmax 0.4242E−03 0.6 Hmax0.7813E−03 0.7 Hmax 0.1341E−02 0.8 Hmax 0.2226E−02 0.9 Hmax 0.3774E−021.0 Hmax 0.7007E−02 r7 0.1 Hmax 0.1297E−05 0.2 Hmax 0.1048E−04 0.3 Hmax0.3933E−04 0.4 Hmax 0.1182E−03 0.5 Hmax 0.3154E−03 0.6 Hmax 0.7440E−030.7 Hmax 0.1587E−02 0.8 Hmax 0.3342E−02 0.9 Hmax 0.7882E−02 1.0 Hmax0.2168E−01 (17) φ * (N′ − N) * d/dH{X(H) − X0(H)} r14 0.1 Hmax−0.1376E−05 0.2 Hmax −0.1096E−04 0.3 Hmax −0.3674E−04 0.4 Hmax−0.8634E−04 0.5 Hmax −0.1670E−03 0.6 Hmax −0.2856E−03 0.7 Hmax−0.4493E−03 0.8 Hmax −0.6655E−03 0.9 Hmax −0.9425E−03 1.0 Hmax−0.1289E−02 r15 0.1 Hmax 0.2247E−05 0.2 Hmax 0.1897E−04 0.3 Hmax0.7022E−04 0.4 Hmax 0.1900E−03 0.5 Hmax 0.4395E−03 0.6 Hmax 0.9265E−030.7 Hmax 0.1830E−02 0.8 Hmax 0.3428E−02 0.9 Hmax 0.6120E−02 1.0 Hmax0.1044E−01 r18 0.1 Hmax −0.2409E−06 0.2 Hmax −0.1935E−05 0.3 Hmax−0.6567E−05 0.4 Hmax −0.1564E−04 0.5 Hmax −0.3061E−04 0.6 Hmax−0.5263E−04 0.7 Hmax −0.8235E−04 0.8 Hmax −0.1197E−03 0.9 Hmax−0.1645E−03 1.0 Hmax −0.2188E−03 r19 0.1 Hmax 0.2249E−06 0.2 Hmax0.1798E−05 0.3 Hmax 0.6062E−05 0.4 Hmax 0.1435E−04 0.5 Hmax 0.2800E−040.6 Hmax 0.4842E−04 0.7 Hmax 0.7715E−04 0.8 Hmax 0.1161E−03 0.9 Hmax0.1681E−03 1.0 Hmax 0.2372E−03 [Embodiment 2]  (1) f1/f1W: 7.50  (2)f2/f1W: −1.10  (3) f3/f1W: 1.27  (4) img * R: 7.8  (5) Ra/f3: 0.59  (6)R2n/f2: −0.73   (6)′ f2p/f2: —  (7) νn: 29.85  (8) νp: 52.69  (9) m1/Z:1.69 (10) M1WM/M1MT: 1.33 (11) max(T1,T2,T3)/f1W: 2.19 (12) Lw/f1W: 7.80(13) Δβ3/Δβ2: 0.479 (14) βT2/βw2: 4.45 (15) fT/|f12W|: 6.05 (16) φ * (N′− N) * d/dH{X(H) − X0(H)} r11 0.1 Hmax 0.2295E−05 0.2 Hmax 0.1801E−040.3 Hmax 0.5851E−04 0.4 Hmax 0.1298E−03 0.5 Hmax 0.2285E−03 0.6 Hmax0.3386E−03 0.7 Hmax 0.4304E−03 0.8 Hmax 0.4548E−03 0.9 Hmax 0.3054E−031.0 Hmax −0.3160E−03 r13 0.1 Hmax −0.2424E−04 0.2 Hmax −0.1929E−03 0.3Hmax −0.6441E−03 0.4 Hmax −0.1498E−02 0.5 Hmax −0.2841E−02 0.6 Hmax−0.4713E−02 0.7 Hmax −0.7112E−02 0.8 Hmax −0.1000E−01 0.9 Hmax−0.1329E−01 1.0 Hmax −0.1657E−01 (17) φ * (N′ − N) * d/dH{X(H) − X0(H)}r15 0.1 Hmax −0.8171E−05 0.2 Hmax −0.6760E−04 0.3 Hmax −0.2402E−03 0.4Hmax −0.6071E−03 0.5 Hmax −0.1276E−02 0.6 Hmax −0.2397E−02 0.7 Hmax−0.4202E−02 0.8 Hmax −0.7142E−02 0.9 Hmax −0.1222E−01 1.0 Hmax−0.2174E−01 r21 0.1 Hmax 0.7678E−06 0.2 Hmax 0.6178E−05 0.3 Hmax0.2110E−04 0.4 Hmax 0.5108E−04 0.5 Hmax 0.1031E−03 0.6 Hmax 0.1871E−030.7 Hmax 0.3174E−03 0.8 Hmax 0.5169E−03 0.9 Hmax 0.8243E−03 1.0 Hmax0.1311E−02 r22 0.1 Hmax −0.6757E−05 0.2 Hmax −0.5453E−04 0.3 Hmax−0.1858E−03 0.4 Hmax −0.4430E−03 0.5 Hmax −0.8648E−03 0.6 Hmax−0.1486E−02 0.7 Hmax −0.2345E−02 0.8 Hmax −0.3487E−02 0.9 Hmax−0.4902E−02 1.0 Hmax −0.6245E−02 Embodiment 3]  (1) f1/f1W: 7.50  (2)f2/f1W: −1.08  (3) f3/f1W: 1.29  (4) img * R: 7.8  (5) Ra/f3: 0.58  (6)R2n/f2: −0.72   (6)′ f2p/f2: −1.72  (7) νn: 27.49  (8) νp: 61.49  (9)m1/Z: 1.64 (10) M1WM/M1MT: 1.99 (11) max(T1,T2,T3)/f1W: 2.15 (12)Lw/f1W: 7.80 (13) Δβ3/Δβ2: 0.276 (14) βT2/βw2: 5.87 (15) fT/|f12W|: 6.30(16) φ * (N′ − N) * d/dH{X(H) − X0(H)} r11 0.1 Hmax 0.4444E−05 0.2 Hmax0.3516E−04 0.3 Hmax 0.1157E−03 0.4 Hmax 0.2617E−03 0.5 Hmax 0.4735E−030.6 Hmax 0.7325E−03 0.7 Hmax 0.1005E−02 0.8 Hmax 0.1248E−02 0.9 Hmax0.1387E−02 1.0 Hmax 0.1160E−02 r13 0.1 Hmax −0.2158E−04 0.2 Hmax−0.1719E−03 0.3 Hmax −0.5752E−03 0.4 Hmax −0.1343E−02 0.5 Hmax−0.2562E−02 0.6 Hmax −0.4292E−02 0.7 Hmax −0.6580E−02 0.8 Hmax−0.9480E−02 0.9 Hmax −0.1306E−01 1.0 Hmax −0.1722E−01 (17) φ * (N′ −N) * d/dH{X(H) − X0(H)} r15 0.1 Hmax −0.8057E−05 0.2 Hmax −0.6645E−040.3 Hmax −0.2351E−03 0.4 Hmax −0.5916E−03 0.5 Hmax −0.1238E−02 0.6 Hmax−0.2316E−02 0.7 Hmax −0.4041E−02 0.8 Hmax −0.6824E−02 0.9 Hmax−0.1156E−01 1.0 Hmax −0.2027E−01 r21 0.1 Hmax 0.1954E−05 0.2 Hmax0.1575E−04 0.3 Hmax 0.5397E−04 0.4 Hmax 0.1312E−03 0.5 Hmax 0.2662E−030.6 Hmax 0.4849E−03 0.7 Hmax 0.8255E−03 0.8 Hmax 0.1346E−02 0.9 Hmax0.2142E−02 1.0 Hmax 0.3882E−02 r22 0.1 Hmax −0.5091E−05 0.2 Hmax−0.4136E−04 0.3 Hmax −0.1423E−03 0.4 Hmax −0.3433E−03 0.5 Hmax−0.6782E−03 0.6 Hmax −0.1180E−02 0.7 Hmax −0.1882E−02 0.8 Hmax−0.2822E−02 0.9 Hmax −0.3966E−02 1.0 Hmax −0.4941E−02 [Embodiment 4] (1) f1/f1W: 7.50  (2) f2/f1W: −0.77  (3) f3/f1W: 1.56  (4) img * R: 9.0 (5) Ra/f3: 0.67  (6) R2n/f2: −0.83   (6)′ f2p/f2: —  (7) νn: 23.23  (8)νp: 56.38  (9) m1/Z: 0.77 (10) M1WM/M1MT: 1.89 (11) max(T1,T2,T3)/f1W:2.76 (12) Lw/f1w: 7.80 (13) Δβ3/Δβ2: 0.519 (14) βT2/βw2: 4.29 (15)fT/|f12W|: 7.56 (16) φ * (N′ − N) * d/dH{X(H) − X0(H)} r6 0.1 Hmax0.4744E−05 0.2 Hmax 0.3648E−04 0.3 Hmax 0.1159E−03 0.4 Hmax 0.2559E−030.5 Hmax 0.4680E−03 0.6 Hmax 0.7769E−03 0.7 Hmax 0.1241E−02 0.8 Hmax0.1973E−02 0.9 Hmax 0.3146E−02 1.0 Hmax 0.4992E−02 r7 0.1 Hmax0.7598E−05 0.2 Hmax 0.5904E−04 0.3 Hmax 0.1937E−03 0.4 Hmax 0.4552E−030.5 Hmax 0.9051E−03 0.6 Hmax 0.1632E−02 0.7 Hmax 0.2839E−02 0.8 Hmax0.5410E−02 0.9 Hmax 0.1304E−01 1.0 Hmax 0.3824E−01 (17) φ * (N′ − N) *d/dH{X(H) − X0(H)} r14 0.1 Hmax 0.4440E−06 0.2 Hmax 0.3521E−05 0.3 Hmax0.1170E−04 0.4 Hmax 0.2711E−04 0.5 Hmax 0.5127E−04 0.6 Hmax 0.8491E−040.7 Hmax 0.1279E−03 0.8 Hmax 0.1796E−03 0.9 Hmax 0.2412E−03 1.0 Hmax0.3202E−03 r15 0.1 Hmax 0.1798E−05 0.2 Hmax 0.1558E−04 0.3 Hmax0.5975E−04 0.4 Hmax 0.1678E−03 0.5 Hmax 0.4013E−03 0.6 Hmax 0.8676E−030.7 Hmax 0.1740E−02 0.8 Hmax 0.3263E−02 0.9 Hmax 0.5719E−02 1.0 Hmax0.9272E−02 r18 0.1 Hmax 0.9843E−08 0.2 Hmax 0.7949E−07 0.3 Hmax0.2721E−06 0.4 Hmax 0.6562E−06 0.5 Hmax 0.1305E−05 0.6 Hmax 0.2297E−050.7 Hmax 0.3737E−05 0.8 Hmax 0.5826E−05 0.9 Hmax 0.9094E−05 1.0 Hmax0.1493E−04 r19 0.1 Hmax −0.4833E−06 0.2 Hmax −0.3850E−05 0.3 Hmax−0.1290E−04 0.4 Hmax −0.3032E−04 0.5 Hmax −0.5870E−04 0.6 Hmax−0.1008E−03 0.7 Hmax −0.1604E−03 0.8 Hmax −0.2436E−03 0.9 Hmax−0.3623E−03 1.0 Hmax −0.5391E−03 [Embodiment 5]  (1) f1/f1W: 8.48  (2)f2/f1W: −1.07  (3) f3/f1W: 1.55  (4) img * R: 7.86  (5) Ra/f3: 0.80  (6)R2n/f2: −1.03   (6)′ f2p/f2: −1.92  (7) νn: 25.00  (8) νp: 70.44, 61.66 (9) m1/Z: 2.46 (10) M1WM/M1MT: 0.98 (11) max(T1,T2,T3)/f1W: 1.68 (12)Lw/f1W: 7.80 (13) Δβ3/Δβ2: 0.790 (14) βT2/βw2: 3.47 (15) fT/|f12W|: 6.66(16) φ * (N′ − N) * d/dH{X(H) − X0(H)} r11 0.1 Hmax 0.1206E−04 0.2 Hmax0.9798E−04 0.3 Hmax 0.3307E−03 0.4 Hmax 0.7526E−03 0.5 Hmax 0.1327E−020.6 Hmax 0.1931E−02 0.7 Hmax 0.2446E−02 0.8 Hmax 0.2890E−02 0.9 Hmax0.3121E−02 1.0 Hmax 0.9253E−03 r13 0.1 Hmax −0.6375E−05 0.2 Hmax−0.5121E−04 0.3 Hmax −0.1730E−03 0.4 Hmax −0.4062E−03 0.5 Hmax−0.7737E−03 0.6 Hmax −0.1280E−02 0.7 Hmax −0.1917E−02 0.8 Hmax−0.2672E−02 0.9 Hmax −0.3528E−02 1.0 Hmax −0.4352E−02 (17) φ * (N′ −N) * d/dH{X(H) − X0(H)} r22 0.1 Hmax 0.1382E−04 0.2 Hmax 0.1107E−03 0.3Hmax 0.3761E−03 0.4 Hmax 0.9042E−03 0.5 Hmax 0.1810E−02 0.6 Hmax0.3244E−02 0.7 Hmax 0.5408E−02 0.8 Hmax 0.8589E−02 0.9 Hmax 0.1329E−011.0 Hmax 0.2059E−01 [Embodiment 6]  (1) f1/f1W: 7.96  (2) f2/f1W: −1.07 (3) f3/f1W: 1.47  (4) img * R: 8.77  (5) Ra/f3: 1.07  (6) R2n/f2: −1.01  (6)′ f2p/f2: —  (7) νn: 22.60  (8) νp: 42.83, 51.57  (9) m1/Z: 2.11(10) M1WM/M1MT: 1.32 (11) max(T1,T2,T3)/f1W: 2.15 (12) Lw/f1W: 7.96 (13)Δβ3/Δβ2: 0.870 (14) βT2/βw2: 3.31 (15) fT/|f12W|: 6.33 (16) φ * (N′ −N) * d/dH{X(H) − X0(H)} r8 0.1 Hmax 0.3517E−06 0.2 Hmax 0.4295E−05 0.3Hmax 0.1921E−04 0.4 Hmax 0.4923E−04 0.5 Hmax 0.8826E−04 0.6 Hmax0.1401E−03 0.7 Hmax 0.2507E−03 0.8 Hmax 0.3569E−03 0.9 Hmax −0.6708E−031.0 Hmax −0.8220E−02 r14 0.1 Hmax −0.2459E−06 0.2 Hmax −0.1948E−05 0.3Hmax −0.6476E−05 0.4 Hmax −0.1508E−04 0.5 Hmax −0.2892E−04 0.6 Hmax−0.4910E−04 0.7 Hmax −0.7656E−04 0.8 Hmax −0.1115E−03 0.9 Hmax−0.1517E−03 1.0 Hmax −0.1895E−03 (17) φ * (N′ − N) * d/dH{X(H) − X0(H)}r16 0.1 Hmax −0.5975E−05 0.2 Hmax −0.4791E−04 0.3 Hmax −0.1625E−03 0.4Hmax −0.3888E−03 0.5 Hmax −0.7699E−03 0.6 Hmax −0.1354E−02 0.7 Hmax−0.2196E−02 0.8 Hmax −0.3359E−02 0.9 Hmax −0.4945E−02 1.0 Hmax−0.7194E−02 r23 0.1 Hmax 0.1179E−05 0.2 Hmax 0.9551E−05 0.3 Hmax0.3271E−04 0.4 Hmax 0.7834E−04 0.5 Hmax 0.1535E−03 0.6 Hmax 0.2646E−030.7 Hmax 0.4201E−03 0.8 Hmax 0.6324E−03 0.9 Hmax 0.9092E−03 1.0 Hmax0.1202E−02 [Embodiment 7]  (1) f1/f1W: 5.39  (2) f2/f1W: −0.92  (3)f3/f1W: 1.56  (4) img * R: 8.65  (5) Ra/f3: 0.60  (6) R2n/f2: −1.28  (6)′ f2p/f2: —  (7) νn: 23.23  (8) νp: 56.38, 51.57  (9) m1/Z: 1.01(10) M1WM/M1MT: 2.19 (11) max(T1,T2,T3)/f1W: 2.15 (12) Lw/f1W: 7.84 (13)Δβ3/Δβ2: 0.33 (14) βT2/βw2: 5.38 (15) fT/|f12W|: 6.96 (16) φ * (N′ −N) * d/dH{X(H) − X0(H)} r6 0.1 Hmax 0.1113E−04 0.2 Hmax 0.8527E−04 0.3Hmax 0.2690E−03 0.4 Hmax 0.5852E−03 0.5 Hmax 0.1038E−02 0.6 Hmax0.1624E−02 0.7 Hmax 0.2347E−02 0.8 Hmax 0.3241E−02 0.9 Hmax 0.4473E−021.0 Hmax 0.6691E−02 r7 0.1 Hmax 0.2017E−04 0.2 Hmax 0.1590E−03 0.3 Hmax0.5252E−03 0.4 Hmax 0.1214E−02 0.5 Hmax 0.2307E−02 0.6 Hmax 0.3872E−020.7 Hmax 0.5938E−02 0.8 Hmax 0.8459E−02 0.9 Hmax 0.1134E−01 1.0 Hmax0.1472E−01 (17) φ * (N′ − N) * d/dH{X(H) − X0(H)} r12 0.1 Hmax−0.8522E−05 0.2 Hmax −0.6876E−04 0.3 Hmax −0.2358E−03 0.4 Hmax−0.5737E−02 0.5 Hmax −0.1164E−02 0.6 Hmax −0.2120E−02 0.7 Hmax−0.3599E−02 0.8 Hmax −0.5820E−02 0.9 Hmax −0.9017E−02 1.0 Hmax−0.1369E−01 r19 0.1 Hmax −0.3652E−05 0.2 Hmax −0.2909E−04 0.3 Hmax−0.9732E−04 0.4 Hmax −0.2273E−03 0.5 Hmax −0.4326E−03 0.6 Hmax−0.7148E−03 0.7 Hmax −0.1047E−02 0.8 Hmax −0.1347E−02 0.9 Hmax−0.1419E−02 1.0 Hmax −0.8695E−03 [Embodiment 8]  (1) f1/f1W: 6.53  (2)f2/f1W: −1.25  (3) f3/f1W: 1.82  (4) img * R: 7.07  (5) Ra/f3: 0.72  (6)R2n/f2: −0.83   (6)′ f2p/f2: —  (7) νn: 21.00  (8) νp: 70.44, 61.66  (9)m1/Z: 0.76 (10) M1WM/M1MT: 1.94 (11) max(T1,T2,T3)/f1W: 1.24 (12)Lw/f1W: 9.25 (13) Δβ3/Δβ2: 0.57 (14) βT2/βw2: 4.12 (15) fT/|f12W|: −5.06(16) φ * (N′ − N) * d/dH{X(H) − X0(H)} r11 0.1 Hmax −0.5397E−05 0.2 Hmax−0.3734E−04 0.3 Hmax −0.9832E−04 0.4 Hmax −0.1665E−03 0.5 Hmax−0.2431E−03 0.6 Hmax −0.4716E−03 0.7 Hmax −0.1351E−02 0.8 Hmax−0.4072E−02 0.9 Hmax −0.1099E−01 1.0 Hmax −0.2626E−01 r12 0.1 Hmax−0.1817E−06 0.2 Hmax −0.1062E−05 0.3 Hmax −0.1601E−05 0.4 Hmax0.1705E−05 0.5 Hmax 0.1351E−04 0.6 Hmax 0.3528E−04 0.7 Hmax 0.5683E−040.8 Hmax 0.4287E−04 0.9 Hmax −0.8661E−04 1.0 Hmax −0.4831E−03 (17) φ *(N′ − N) * d/dH{X(H) − X0(H)} r18 0.1 Hmax −0.3199E−04 0.2 Hmax−0.2519E−03 0.3 Hmax −0.8291E−03 0.4 Hmax −0.1903E−02 0.5 Hmax−0.3584E−02 0.6 Hmax −0.5972E−02 0.7 Hmax −0.9181E−02 0.8 Hmax−0.1337E−01 0.9 Hmax −0.1876E−01 1.0 Hmax −0.2560E−01 r19 0.1 Hmax−0.2764E−04 0.2 Hmax −0.2166E−03 0.3 Hmax −0.7063E−03 0.4 Hmax−0.1597E−02 0.5 Hmax −0.2939E−02 0.6 Hmax −0.4737E−02 0.7 Hmax−0.6968E−02 0.8 Hmax −0.9612E−02 0.9 Hmax −0.1270E−01 1.0 Hmax−0.1640E−01 [Embodiment 9]  (1) f1/f1W: 4.80  (2) f2/f1W: −0.76  (3)f3/f1W: 1.55  (4) img * R: 9.95  (5) Ra/f3: 0.81  (6) R2n/f2: −0.84  (6)′ f2p/f2: −2.68  (7) νn: 24.6  (8) νp: 59.25, 59.03  (9) m1/Z: 1.45(10) M1WM/M1MT: 0.90 (11) max(T1,T2,T3)/f1W: 1.43 (12) Lw/f1W: 7.81 (13)Δβ3/Δβ2: 0.78 (14) βT2/βw2: 3.50 (15) fT/|f12W|: 7.86 (16) φ * (N′ −N) * d/dH{X(H) − X0(H)} r11 0.1 Hmax 0.2295E−05 0.2 Hmax 0.1801E−04 0.3Hmax 0.5851E−04 0.4 Hmax 0.1298E−03 0.5 Hmax 0.2285E−03 0.6 Hmax0.3386E−03 0.7 Hmax 0.4304E−03 0.8 Hmax 0.4548E−03 0.9 Hmax 0.3054E−031.0 Hmax 0.3160E−03 (17) φ * (N′ − N) * d/dH{X(H) − X0(H)} r13 0.1 Hmax−0.2424E−04 0.2 Hmax −0.1929E−03 0.3 Hmax −0.6441E−03 0.4 Hmax−0.1498E−02 0.5 Hmax −0.2841E−02 0.6 Hmax −0.4713E−02 0.7 Hmax−0.7112E−02 0.8 Hmax −0.1000E−01 0.9 Hmax −0.1329E−01 1.0 Hmax−0.1657E−01 r15 0.1 Hmax −0.8171E−05 0.2 Hmax −0.6760E−04 0.3 Hmax−0.2402E−03 0.4 Hmax −0.6071E−03 0.5 Hmax −0.1276E−02 0.6 Hmax−0.2397E−02 0.7 Hmax −0.4202E−02 0.8 Hmax −0.7142E−02 0.9 Hmax−0.1222E−01 1.0 Hmax −0.2174E−01 r21 0.1 Hmax 0.7678E−04 0.2 Hmax0.6178E−03 0.3 Hmax 0.2110E−03 0.4 Hmax 0.5108E−02 0.5 Hmax 0.1031E−020.6 Hmax 0.1871E−02 0.7 Hmax 0.3174E−02 0.8 Hmax 0.5169E−02 0.9 Hmax0.8243E−01 1.0 Hmax 0.1311E−01 r22 0.1 Hmax −0.6757E−05 0.2 Hmax−0.5453E−04 0.3 Hmax −0.1858E−03 0.4 Hmax −0.4430E−03 0.5 Hmax−0.8648E−03 0.6 Hmax −0.1486E−02 0.7 Hmax −0.2345E−02 0.8 Hmax−0.3487E−02 0.9 Hmax −0.4902E−02 1.0 Hmax −0.6245E−02

[0204] As described above in detail, according to the invention, it ispossible to provide a zoom lens system which is compact although thesystem can satisfy requirements of a high variable magnification and ahigh image quality.

[0205] Therefore, when the zoom lens system of the invention is appliedto an imaging optical system of a digital camera, the zoom lens systemcan contribute to a high performance and compactness of the camera.

[0206] Reasonable variations and modifications of the invention arepossible within the scope of the foregoing description, the drawings andthe appended claims to the invention.

1. A zoom lens system comprising, from an object side of the zoom lenssystem to an image side of the zoom lens system: a first lens unithaving a positive optical power, the first lens unit being movable in azooming operation: a second lens unit having a negative optical power;and a third lens unit having a positive optical power; wherein a zoomingoperation is performed by varying distances between adjacent ones of thefirst, second, and third lens units; and wherein the zoom lens systemsatisfies the following condition: 0.8<M 1 WM/M 1 MT<2.5  where M1WMrepresents a movement amount of the first lens unit from a shortestfocal length condition to a middle focal length condition; and M1MTrepresents a movement amount of the first lens unit from the middlefocal length condition to a longest focal length condition, the middlefocal length being a focal length which is (fW/fT)^(1/2) where fW is afocal length of the entire zoom lens system at the shortest focal lengthcondition and fT is a focal length of the entire zoom lens system at thelongest focal length condition.
 2. A zoom lens system as claimed inclaim 1, wherein the first and third lens unit are movable in a zoomingoperation so that a first distance between the first and second lensunits increases and a second distance between the second and third lensunits decreases.
 3. A zoom lens system as claimed in claim 1, whereinthe first, second, and third lens units are movable in a zoomingoperation so that a first distance between the first and second lensunits increases and a second distance between the second and third lensunits decreases.
 4. A zoom lens system comprising, from an object sideof the zoom lens system to an image side of the zoom lens system: afirst lens unit having a positive optical power, the first lens unitbeing movable in a zooming operation; a second lens unit having anegative optical power; and a third lens unit having a positive opticalpower; wherein a zooming operation is performed by varying distancesbetween adjacent ones of the first, second, and third lens units; andwherein the zoom lens system satisfies the following condition:0.2<Δβ3/Δβ2<1.0  where Δβ2 represents a ratio of a lateral magnification(lateral magnification at a longest focal length condition/lateralmagnification at a shortest focal length condition) of the second lensunit; and Δβ3 represents a ratio of a lateral magnification (lateralmagnification at the longest focal length condition/lateralmagnification at the shortest focal length condition) of the third lensunit.
 5. A zoom lens system as claimed in claim 4, wherein the first andthird lens units are movable in a zooming operation so that a firstdistance between the first and second lens units increases and a seconddistance between the second and third lens units decreases.
 6. A zoomlens system as claimed in claim 4, wherein the first, second, and thirdlens unit are movable in a zooming operation so that a first distancebetween the first and second lens units increases and a second distancebetween the second and third lens units decreases.
 7. A zoom lens systemcomprising, from an object side of the zoom lens system to an image sideof the zoom lens system: a first lens unit having a positive opticalpower, the first lens unit being movable in a zooming operation; asecond lens unit having a negative optical power; and a third lens unithaving a positive optical power; wherein a zooming operation isperformed by varying distances between adjacent ones of the first,second, and third lens units; and wherein the zoom lens system satisfiesthe following condition: 0.7<m 1 /Z<3.0  where m1 represents a movementamount of the first lens unit in a zooming operation from a shortestfocal length condition to a longest focal length condition; and Zrepresents a zoom ratio (Z=fT/fW where fW is a focal length of theentire zoom lens system at the shortest focal length condition and fT isa focal length of the entire zoom lens unit at the longest focal lengthcondition).
 8. A zoom lens system as claimed in claim 7, wherein thefirst and third lens units are movable in a zooming operation so that afirst distance between the first and second lens units increases and asecond distance between the second and third lens units decreases.
 9. Azoom lens system as claimed in claim 7, wherein the first, second, andthird lens unit are movable in a zooming operation so that a firstdistance between the first and second lens units increases and a seconddistance between the second and third lens units decreases.
 10. A zoomlens system comprising, from an object side of the zoom lens system toan image side of the zoom lens system: a first lens unit having apositive optical power, the first lens unit being movable in a zoomingoperation; a second lens unit having a negative optical power; and athird lens unit having a positive optical power; wherein a zoomingoperation is performed by varying distances between the first, second,and third lens units; and wherein the zoom lens system satisfies thefollowing condition: 1.0<img*R<15.0  where img represents a maximumimage height; and R represents an effective diameter of a lens surfacewhich is closest to the image side among lens surfaces constituting thezoom lens system.
 11. A zoom lens system as claimed in claim 10, whereinthe first and third lens units are movable in a zooming operation sothat a first distance between the first and second lens units increasesand a second distance between the second and third lens units decreases.12. A zoom lens system as claimed in claim 10, wherein the first,second, and third lens unit are movable in the zooming operation so thata first distance between the first and second lens units increases and asecond distance between the second and third lens units decreases.
 13. Azoom lens system as claimed in claim 10, wherein the third lens unitcomprises, in sequence along an optical axis extending from the objectside to the image side, a positive lens element having a convex surfaceon its object side and a negative lens element.
 14. A zoom lens systemcomprising, from an object side of the zoom lens system to an image sideof the zoom lens system: a first lens unit having a positive opticalpower, the first lens unit being moved in a zooming operation; a secondlens unit having a negative optical power; and a third lens unit havinga positive optical power; wherein the zooming operation is performed byvarying distances between the first, second and third lens units,wherein the zoom lens system satisfies the following conditions:1.0<max(T 1,T 2,T 3)/fW<44.5<fT/|f 12 W|<15  where Ti is an axialthickness of an i-th unit; max(T1, T2, T3) is a maximum value ofthickness; fT represents a focal length at a longest focal lengthcondition; and f12W represents a composite focal length of the first andsecond lens units at a shortest focal length condition.
 15. A zoom lenssystem as claimed in claim 14, wherein the first and third lens unitsare movable in a zooming operation so that a first distance between thefirst and second lens units increases and a second distance between thesecond and third lens units decreases.
 16. A zoom lens system as claimedin claim 14, wherein the first, second, and third lens unit are movablein a zooming operation so that a first distance between the first andsecond lens units increases and a second distance between the second andthird lens units decreases.
 17. Apparatus comprising: a solid stateimaging device; filters; and a zoom lens system for forming an image ofan object on said solid state imaging device; wherein said zoom lenssystem comprises, from an object side of the zoom lens system to animage side of the zoom lens system; a first lens unit having a positiveoptical power, the first lens unit being movable in a zooming operation;a second lens unit having a negative optical power; and a third lensunit having a positive optical power; and wherein said filters areprovided between the lens units and the solid state imaging device andinclude an optical low-pass filter and an infrared blocking filter,wherein a zooming operation is performed by varying distances betweenthe first, second, and third lens units; and wherein the zoom lenssystem satisfies the following condition: 0.8<M 1 WM/M 1 MT<2.5  whereM1WM represents a movement amount of the first lens unit from a shortestfocal length condition to a middle focal length condition; and M1MTrepresents a movement amount of the first lens unit from the middlefocal length condition to a longest focal length condition, the middlefocal length being a focal length which is (fW/fT)^(1/2) where fW is afocal length of the entire zoom lens system at the shortest focal lengthcondition and fT is a focal length of the entire zoom lens unit at thelongest focal length condition.
 18. Apparatus comprising: a solid stateimaging device; filters; and a zoom lens system for forming an image ofan object on said solid state imaging device, said zoom lens systemcomprising, from an object side of the zoom lens system to an image sideof said zoom lens system: a first lens unit having a positive opticalpower, the first lens unit being movable in a zooming operation: asecond lens unit having a negative optical power; and a third lens unithaving a positive optical power; wherein said filters are providedbetween the lens units and the solid state imaging device and include anoptical low-pass filter and an infrared blocking filter; wherein azooming operation is performed by varying distances between the first,second, and third lens units; and wherein the zoom lens system satisfiesthe following condition: 0.2<Δβ3/Δβ2<1.0  where Δβ2 represents a ratioof a lateral magnification at a longest focal length condition of thesecond lens unit to a lateral magnification at a shortest focal lengthcondition of the second lens unit; and Δβ3 represents a ratio of alateral magnification at a longest focal length condition of the thirdlens unit to a lateral magnification at a shortest focal lengthcondition of the third lens unit.
 19. Apparatus comprising: a solidstate imaging device; filters; and a zoom lens system for forming animage of an object on said solid state imaging device, the zoom lenssystem comprising from an object side of the zoom lens system to animage side of the zoom lens system: a first lens unit having a positiveoptical power, the first lens unit being movable in a zooming operation;a second lens unit having a negative optical power; and a third lensunit having a positive optical power; wherein said filters are providedbetween the lens units and the solid state imaging device and include anoptical low-pass filter and an infrared blocking filter; wherein azooming operation is performed by varying distances between adjacentones of the first, second, and third lens units; and wherein the zoomlens system satisfies the following condition: 0.7<m 1/Z<3.0  where M1represents a movement amount of the first lens unit in a zoomingoperation from a shortest focal length condition to a longest focallength condition; and Z represents a zoom ratio (Z=fT/fW: where fW is afocal length of the entire zoom lens system at the shortest focal lengthcondition and fT is a focal length of the entire zoom lens unit at thelongest focal length condition).
 20. Apparatus comprising: a solid stateimaging device; filters; and a zoom lens system for forming an image ofan object on the solid state imaging device, the zoom lens systemcomprising, from an object side of the zoom lens system to an image sideof the zoom lens system: a first lens unit having a positive opticalpower, the first lens unit being movable in a zooming operation; asecond lens unit having a negative optical power; and a third lens unithaving a positive optical power; wherein said filters are providedbetween the lens units and the solid state imaging device and include anoptical low-pass filter and an infrared blocking filter, wherein azooming operation is performed by varying distances between adjacentones of the first, second, and third lens units, wherein the zoom lenssystem satisfies the following condition: 1.0<img*R<15.0  where imgrepresents a maximum image height; and R represents an effectivediameter of a lens surface which is closest to the image side of thezoom lens system among lens surfaces constituting the zoom lens system.